In addition to the Firefox release I mentioned in the previous post, Mozilla has also released a new version, 3.1.11, of its Thunderbird E-mail client, for all platforms: Mac OS X, Linux, and Windows. (Mozilla often makes simultaneous releases of Thunderbird and Firefox, since the two applications share a considerable code base.) This release includes fixes for several security and stability bugs; more information is in the Release Notes.
You can get the new version using the built-in update mechanism (Help -> Check for Updates); alternatively, you can download an installation package (in a variety of natural languages) here. Because of the security fixes included, I recommend installing the new version as soon as you conveniently can.