Version:           unspecified (using KDE 4.7.2) 
OS:                Linux

Everytime you try to connect to a wifi, you can see the "secrets of <wifiname>" window in which you must enter wifi password.
So knetworkmanager does not save wifi passwords.
I am not 100% sure, but even if you enable kde wallet you have this problem (on Fedora 15 this happened also with KDE wallet)

OS: Fedora 16 KDE


yum list | grep plasma
kde-plasma-networkmanagement.i686     1:0.9-0.65.rc2.nm09.fc16 @anaconda-0      
kde-plasma-networkmanagement-debuginfo.i686
kde-plasma-networkmanagement-libs.i686
kde-settings-plasma.noarch            4.7-13.fc16.4            @anaconda-0      
plasma-scriptengine-python.i686       4.7.2-14.fc16            @anaconda-0      
kde-plasma-activitymanager.i686       0.5-2.fc16               fedora           
kde-plasma-activitymanager-debuginfo.i686
kde-plasma-daisy.i686                 0.0.4.25-2.fc15          fedora           
kde-plasma-daisy-debuginfo.i686       0.0.4.25-2.fc15          fedora-debuginfo 
kde-plasma-ihatethecashew.i686        0.4-3.fc15               fedora           
kde-plasma-ihatethecashew-debuginfo.i686
kde-plasma-ktorrent.i686              4.1.2-1.fc16             fedora           
kde-plasma-networkmanagement-openconnect.i686
kde-plasma-networkmanagement-openvpn.i686
kde-plasma-networkmanagement-pptp.i686
kde-plasma-networkmanagement-vpnc.i686
kde-plasma-qstardict.i686             1.0-2.fc16               fedora           
kde-plasma-quickaccess.i686           0.8.1-5.fc16             fedora           
kde-plasma-quickaccess-debuginfo.i686 0.8.1-5.fc16             fedora-debuginfo 
kde-plasma-runcommand.i686            2.2-2.fc15               fedora           
kde-plasma-runcommand-debuginfo.i686  2.2-2.fc15               fedora-debuginfo 
kde-plasma-smooth-tasks.i686          0.0.1-0.2.wip20101106.fc15
kde-plasma-smooth-tasks-debuginfo.i686
kde-plasma-translatoid.i686           1.30-3.svn01092011.fc15  fedora           
kde-plasma-translatoid-debuginfo.i686 1.30-3.svn01092011.fc15  fedora-debuginfo 
kde-plasma-yawp.i686                  0.3.6-2.fc15             fedora           
kde-plasma-yawp-debuginfo.i686        0.3.6-2.fc15             fedora-debuginfo 
kdeplasma-addons.i686                 4.7.2-1.fc16             fedora           
kdeplasma-addons-debuginfo.i686       4.7.2-1.fc16             fedora-debuginfo 
kdeplasma-addons-devel.i686           4.7.2-1.fc16             fedora           
kdeplasma-addons-libs.i686            4.7.2-1.fc16             fedora           
plasma-scriptengine-ruby.i686         4.7.2-14.fc16            fedora           
plasma-wallpaper-marble.i686          4.7.2-1.fc16             fedora           


Reproducible: Always

Steps to Reproduce:
Connecto to a wifi, then reboot to be sure, and try to connect again. You will prompted again to enter the password


Expected Results:  
You should enter a wifi password only the first time you connect to it, and not other times