...and for a slightly broadened take on matters, the always-interesting Doron Zeilberger:
Meanwhile, 4000+ scientists have signed a petition supporting the boycott idea. This isn't simply a mathematics issue, since Elsevier publishes in several different subject areas -- but frankly, I'm kinda proud (even though I'm not even a professional mathematician myself) that this whole movement was raised to the forefront by a major mathematician. More generally, I'm proud of the pioneering work that mathematicians have done in utilizing the Web as a collaborative force to accomplish things.
The public often perceives mathematicians in a 'geeky,' loner sort of light, working quietly away in a corner, but in fact, when the spirit moves them ;-) they can be among the most powerful (and unselfish) movers of science and society! Give Tim Gowers a high-five!
ADDENDUM: I don't plan to do continuous "Addendums" on this issue, as related pertinent Web posts appear, but I do think the following update from Tim Gowers is worth noting: