When I was a postdoc at Berkeley we wanted to release some open source code. I talked to the professor, who is a really smart guy. We discussed various licenses and I asked about GPL. He said he had read it and simply couldn't understand what it meant, legally speaking. He read the BSD (both types) license and it made perfect sense (same for Apache and MIT).

After thinking for a while and seeing the battles and their outcomes I have concluded that GPL is in fact a liability, not a license.