Adobe has released a new version of both Adobe Reader and Acrobat, which addresses a critical security issue where the program can crash and allow an attacker to take control of the system. This is important for some users, since they may have the reader and accompanied Internet plugin installed for use with Firefox and other browsers that do not use Apple's built-in PDF rendering.
For more information on the security details of this update, see the following Adobe security bulletin: http://www.adobe.com/support/security/bulletins/apsb10-15.html
You can get the latest update for Acrobat from Adobe's website:
Adobe Reader 9.3.0 (For now you must use Adobe Updater to install the latest update for Reader)