Timothy Gowers posted on Google+,

Although it happened about a month ago, I’ve only just heard that John Ball can be added to the list of current and former Presidents of the International Mathematical Union who have signed the Cost of Knowledge boycott. He had to resign from editorships of three Elsevier journals to do so.
While I’m on this kind of topic, there are under two days left to sign the White House open access petition. Although it’s reached 25,000 signatures and will therefore get an official response, it is still the case that the more signatures it gets the better.

Here are the two relevant links.