The major antivirus programs – Windows OneCare, Symantec, McAfee, and more – now catch malicious files exploiting the Windows WMF vulnerability. Here’s an article about the tests done by an independent lab.
If you’re running a standalone version of a Symantec or McAfee product, update your virus definitions! (If you’re running Windows OneCare with a green light, you’re already up to date. If your antivirus program is administered through your company network, your network administrator should already have this covered, right?)