Licensing discussions do tend to be somewhat hormonal; here I express
my own hormones:

http://nipyworld.blogspot.com/2011/01/gp...

Here was our licensing discussion and why we chose BSD:

http://nipy.sourceforge.net/nipy/stable/...

Apart from the hormonal discussion:
1) For an application, chose GPL or BSD to taste
2) For a library, if you chose GPL, or even LGPL, someone will likely
find that they cannot use your library for a licensing reason, and
write a competitive BSD-licensed library.