As seen on slashdot, the author of the ATSC Capture and edit tool has placed a notice of license revokal at sourceforge.net. While the GPLv2-FAQ states that a program licensed under the GPL cannot be re-licenced to someone else exclusively, both the FAQ and the license text itself don’t actually say anything about the license not being irrevokable. While one could interpret the absence of an arbitrary revokation clause (GPv2L can terminate automatically in case of violation) as a hint the license cannot be revoked indeed, a nifty lawyer could well come up with a convincing-sounding argument for the opposite.
Perhaps someone with a proper legal background (FSFE-TF, SFLC anyone?) could contact the author and try to convince him to withdraw that statement. It’s already making its way around the internet, just google for artscap and you’ll come up with a few hits. This might give people the wrong idea and lead more developers to try to revoke licenses for GPL’ed projects.