Well, there have been some changes in that area in git master, including support for the new kde 4.4 systray stuff. So whatever might be the cause for this in 2.3.0 might not exist anymore. :)

commit 26104cd35fd50222c354f3afc9fce6bba093c05f
Author: Kevin Funk <krf@electrostorm.net>
Date:   Thu Jul 8 12:13:00 2010 +0200

    Some TrayIcon changes:
    * Remove track progress effect (this is because KSNI has some bogus
    implementation of the setIconByPixmap() function causing the overlay
    icon being wrong sized
    * Fix overlay icon size
    * Tooltip album cover is now updated if changed in Amarok
    * Cleanup
    CCBUG: 231539
    CCBUG: 232578
    CCBUG: 232312
    BUG: 233506
    BUG: 240463

diff --git a/src/TrayIcon.cpp b/src/TrayIcon.cpp
index fb97483..4bd46e4 100644
--- a/src/TrayIcon.cpp
+++ b/src/TrayIcon.cpp
@@ -52,7 +52,6 @@
 Amarok::TrayIcon::TrayIcon( QObject *parent )
         : KStatusNotifierItem( parent )
         , Engine::EngineObserver( The::engineController() )
-        , m_trackLength( 0 )
         , m_separator( 0 )
 {
     DEBUG_BLOCK
@@ -80,14 +79,8 @@ Amarok::TrayIcon::TrayIcon( QObject *parent )
 
     PERF_LOG( "Adding system tray icon" );
 
-    m_baseIcon = KIconLoader::global()->loadIcon( "amarok", KIconLoader::Panel );
-    setIconByPixmap( m_baseIcon ); // show icon
-    setOverlayIconByName( QString() );
+    setIconByName( "amarok" );
 
-    m_grayedIcon = m_baseIcon; // copies object
-    KIconEffect::semiTransparent( m_grayedIcon );
-
-    paintIcon();
     setupToolTip();
 
     connect( this, SIGNAL( scrollRequested( int, Qt::Orientation ) ), SLOT( slotScrollRequested(int, Qt::Orientation) ) );
@@ -102,22 +95,13 @@ Amarok::TrayIcon::setupToolTip()
         setToolTipTitle( The::engineController()->prettyNowPlaying() );
 
         QStringList tooltip;
-        // TODO: Use Observer to get notified about changed album art
-        if( m_track->album() )
+        if( m_track->album() && m_track->album()->hasImage() )
         {
             const QString uid = m_track->uidUrl();
             if ( uid != m_toolTipIconUid ) {
                 const QPixmap image = The::svgHandler()->imageWithBorder( m_track->album(), KIconLoader::SizeLarge, 5 );
-                if ( image.isNull() )
-                {
-                    setToolTipIconByName( "amarok" );
-                    m_toolTipIconUid.clear();
-                }
-                else
-                {
-                    setToolTipIconByPixmap( image );
-                    m_toolTipIconUid = uid;
-                }
+                setToolTipIconByPixmap( image );
+                m_toolTipIconUid = uid;
             }
         }
         else
@@ -184,9 +168,10 @@ Amarok::TrayIcon::setupToolTip()
     else
     {
         setToolTipIconByName( "amarok" );
-        m_toolTipIconUid.clear();
         setToolTipTitle( KCmdLineArgs::aboutData()->programName() );
         setToolTipSubTitle( The::engineController()->prettyNowPlaying() );
+
+        m_toolTipIconUid.clear();
     }
 }
 
@@ -206,20 +191,26 @@ Amarok::TrayIcon::engineStateChanged( Phonon::State state, Phonon::State /*oldSt
     switch( state )
     {
         case Phonon::PlayingState:
-            unsubscribeFrom( m_track );
+            if ( m_track )
+            {
+                unsubscribeFrom( m_track );
+                unsubscribeFrom( m_track->album() );
+            }
             m_track = track;
-            m_trackLength = m_track ? m_track->length() : 0;
-            subscribeTo( track );
+            if ( track )
+            {
+                subscribeTo( track );
+                subscribeTo( track->album() );
+            }
 
-            paintIcon( 0 );
+            setOverlayIconByName( "media-playback-start" );
             setupMenu();
             break;
 
         case Phonon::StoppedState:
             m_track = 0;
-            m_trackLength = 0;
 
-            paintIcon();
+            setOverlayIconByName( QString() );
             setupMenu(); // remove custom track actions on stop
             break;
 
@@ -230,6 +221,7 @@ Amarok::TrayIcon::engineStateChanged( Phonon::State state, Phonon::State /*oldSt
         case Phonon::LoadingState:
         case Phonon::ErrorState:
         case Phonon::BufferingState:
+            setOverlayIconByName( QString() );
             break;
     }
 
@@ -240,9 +232,6 @@ void
 Amarok::TrayIcon::engineNewTrackPlaying()
 {
     m_track = The::engineController()->currentTrack();
-    m_trackLength = m_track ? m_track->length() : 0;
-
-    paintIcon( 0 );
 
     setupToolTip();
     setupMenu();
@@ -258,12 +247,12 @@ Amarok::TrayIcon::metadataChanged( Meta::TrackPtr track )
 }
 
 void
-Amarok::TrayIcon::engineTrackPositionChanged( qint64 position, bool userSeek )
+Amarok::TrayIcon::metadataChanged( Meta::AlbumPtr album )
 {
-    Q_UNUSED( userSeek );
+    Q_UNUSED( album )
 
-    if( m_trackLength )
-        paintIcon( position );
+    setupToolTip();
+    setupMenu();
 }
 
 void
@@ -283,55 +272,6 @@ Amarok::TrayIcon::engineMuteStateChanged( bool mute )
 }
 
 void
-Amarok::TrayIcon::paletteChange( const QPalette & op )
-{
-    Q_UNUSED( op );
-
-    paintIcon();
-}
-
-void
-Amarok::TrayIcon::paintIcon( qint64 trackPosition )
-{
-    static qint64 oldMergePos = -1;
-
-    // trackPosition < 0 means reset
-    if( trackPosition < 0 )
-    {
-        oldMergePos = -1;
-        setIconByPixmap( m_baseIcon );
-        setOverlayIconByName( QString() );
-        return;
-    }
-
-    // check if we are playing a stream
-    if( !m_trackLength )
-    {
-        m_icon = m_baseIcon;
-        setIconByPixmap( m_icon );
-        setOverlayIconByName( "media-playback-start" );
-        return;
-    }
-
-    const qint64 mergePos = ( float( trackPosition ) / m_trackLength ) * m_icon.height();
-
-    // return if pixmap would stay the same
-    if( oldMergePos == mergePos )
-        return;
-
-    // draw m_baseIcon on top of the gray version
-    m_icon = m_grayedIcon; // copies object
-    QPainter p( &m_icon );
-    p.drawPixmap( 0, 0, m_baseIcon, 0, 0, 0, m_icon.height() - mergePos );
-    p.end();
-
-    oldMergePos = mergePos;
-
-    setIconByPixmap( m_icon );
-    setOverlayIconByName( "media-playback-start" );
-}
-
-void
 Amarok::TrayIcon::setupMenu()
 {
     foreach( QAction* action, m_extraActions )
diff --git a/src/TrayIcon.h b/src/TrayIcon.h
index c2602df..d590b5f 100644
--- a/src/TrayIcon.h
+++ b/src/TrayIcon.h
@@ -49,16 +49,13 @@ protected:
     // reimplemented from engineobserver
     virtual void engineStateChanged( Phonon::State state, Phonon::State oldState = Phonon::StoppedState );
     virtual void engineNewTrackPlaying();
-    virtual void engineTrackPositionChanged( qint64 position, bool /*userSeek*/ );
     virtual void engineVolumeChanged( int percent );
     virtual void engineMuteStateChanged( bool mute );
 
-    //Reimplemented from Meta::Observer
+    // reimplemented from Meta::Observer
     using Observer::metadataChanged;
     virtual void metadataChanged( Meta::TrackPtr track );
-
-    // get notified of 'highlight' color change
-    virtual void paletteChange( const QPalette & oldPalette );
+    virtual void metadataChanged( Meta::AlbumPtr album );
 
 private slots:
     void slotActivated();
@@ -68,13 +65,9 @@ private:
     void setupMenu();
     void setupToolTip();
 
-    void paintIcon( qint64 trackPosition = -1 );
-
     Meta::TrackPtr m_track;
-    qint64 m_trackLength;
     QString m_toolTipIconUid;
 
-    QPixmap m_baseIcon, m_grayedIcon, m_icon;
     SmartPointerList<QAction> m_extraActions;
     QPointer<QAction> m_separator;
 };