Version:           KDE-3-SVN (using KDE KDE 3.5.7)
Installed from:    Compiled From Sources
OS:                Linux

exiv2 is able to write geodata metadata into e.g png files. 
Its easy to tests this: Take a jpeg, add geo-data with the kipi-plugin, open in digikams image editor and save as png. You will see, the geo-data are part of the png metadata. 
 
But you can not add these geo-tag direct into a png, as you can find code like this in this plugin: 
[...] 
// We only add all JPEG files as R/W because Exiv2 can't yet 
// update metadata on others file formats. 
   QFileInfo fi(url.path()); 
   QString ext = fi.extension(false).upper(); 
   bool ret = false; 
   if (ext == QString("JPG") || ext == QString("JPEG") || ext == QString("JPE")) 
   { 
[...] 
 
So, the comment in the source code is definitely wrong and to test the file format a simple extention is used. What about kde standard test to check a filetype based on MIME data? 
 
KMimeType::Ptr type = KMimeType::findByURL("/home/bernd/foobar.jpg"); 
vs 
KMimeMagicResult *result = KMimeMagic::self()->findFileType("/home/bernd/foobar.jpg"); 
 
(from: http://developer.kde.org/documentation/library/kdeqt/kde3arch/mime.html ) 
 
Bye 

  Thorsten 

P.S.
This is a copy of BR148912 that was not forwarded to the developers from the list admin since 14 days. So I had to assign this BR to the wrong package and the digikam devels have additional needless work. Sorry for this.