Shortly after the Elsevier boycott began, Elsevier withdrew its support from the Research Works Act, which immediately led to the act being shelved by its congressional sponsors. Elsevier also announced some new policies for its core mathematics journals.
Nevertheless, the Elsevier boycott continues, and continues to grow.
Henry Cohn and Doug Arnold have written a piece for Notices of the American Mathematical Society, now posted on the arXiv, that discusses several of the most important reasons for the boycott from the point of view of mathematics http://arxiv.org/abs/1204.1351.
If you haven’t yet taken a firm position on the boycott because you haven’t had time to get to grips with the issues of journal pricing and bundling, this article makes a good entry point.