Qt is a cross-platform GUI framework that was recently bought out by Nokia. Until now, Qt has been dual licensed under a commercial license and the GPL. That wasn't very popular with mISVs, because the commercial license is quite expensive, and using the GPL'd version would mean that you'd have to release the code to your own application as well. I also personally don't link the GPL, and prefer a permissive license like MIT for my own non-commercial development.

With the LGPL'd version, software developers will be able to link dynamically to Qt, giving access to the Qt code to their users but keeping their own code proprietary. Note that under the LGPL, if you link statically to Qt, you still need to release your own code as well.

I'm very interested to see if PyQt is also released under the LGPL. If that happens, Qt could become my preferred framework for GUI development (replacing wxPython).