qt and nokia
 

http://www.kde.org/community/whatisk...foundation.php

I do not understand Qt is GPL'ed so how can it be released under a BSD-style license

Because Nokia owns the copyright on Qt after its purchase of Trolltech.

still If I release a project under GPL it's not that easy to release it another license. I have to remove all contributions by third parties.

Therefore I assume Trolltech only has written QT.

If you own all the copyrights on the code you can release it under any license you want even if you have previously released the code under the GPL. Trolltech was the sole owner of QT. If you contributed code to the QT project you had to assign your copyright to Trolltech. In fact, Trolltech dual licensed QT for some time. IIRC QT was free for GPL'd applications but if you wanted to use QT in a proprietary application, you had to pay a license fee to Trolltech.