Lots of law firms were hit with this yesterday, judging from the lawnet listserve traffic. It's a nasty little marketing ploy--get an e-card, get prompted for a download, and if you haven't read the EULA, you don't realize that you're agreeing to this worm download. Very tricky, but you've got to hand it to them for creative business use of a disruptive technology...
First Worm with a EULA? [Slashdot]
It affects Outlook the same way any worm does--mines through your contacts and sends itself out. To prevent your users from accessing the download, block www*friendgreetings*com as well as these two other sites belonging to the same company that owns the current irritant:
www*permissionedmedia*com and www*cool-downloads*com
More information can be found on the Sophos website at