There has been some discussion of the license used in the XIFF library. XIFF is an Actionscript 3 library for XMPP chat.
As I have no comment system on my site, now or never, I ask all people using this library to take part in the discussion at the Igniterealtime community forums. There is also an issue filed for the subject.
Currently XIFF is uses mostly LGPL 2.1 and few files have Apache License v2. Would GPL v3 be a good option?
There has been a lot of discussion of this matter at the FFmpeg developers mailing list as well.
Update 21/08/2009: As of revision 11193, XIFF uses Apache License v2.