The old BSD license is not compatible with the GPL - I assume that if you are allowing proprietary re-use, you would also want to allow as much open source re-sure as possible.
When people say "BSD license" these days they usually mean the "modified BSD license" or "2/3-clause BSD license" that doesn't include the advertising clause, and as such is indeed compatible with the GPL. I don't think anyone of any notoriety actually uses the original, GPL-incompatible BSD license these days.
