If you do nothing else today, make sure you at least upgrade your users to the latest version of Adobe Reader.
The vulnerability was announced back on February 20th, but now Adobe released an update to their Reader product. You can see the bulletin here:
There are a few interesting things to note. As indicated in a post by Ryan Naraine on ZDNet, the updates are for Adobe Reader 9 only. The most frustrating thing right now is that in their infinite wisdom, Adobe did not provide a patch update for Adobe Reader (a file with the MSP extension) which can be applied to your existing installation of Adobe Reader. Instead, they simply point to their standard URL to download Adobe Reader.
Acrobat 9 Standard, Acrobat 9 Pro and Acrobat 9 Extended for Windows are all available as MSP patches.
Don’t wait, upgrade your users as soon as you can because this is a nasty one. Users who download a malicious PDF do not need to open it to fall victim to that flaw.
Hopefully, Adobe will release a patch file for Adobe Reader soon.