The critical flaw that was discovered last week regarding animated cursors at first went with nothing more than a comment in passing from Microsoft. They've changed their tune dramatically now and are quickly moving to provide an emergency patch. This is rare for Microsoft, though not unheard of, whom have been known to delay even critical fixes until enough time has passed for more testing and patch week rolls around. Responding to reports of widespread abuse, Microsoft is planning the emergency patch for tomorrow:

A posting on Microsoft's Security Response Centre blog reports that Microsoft's security gnomes have been working round the clock to produce and test a fix and explains the rationale for Redmond's unusual (but far from unprecedented) decision to publish an out-of-sequence fix. ®
I guess their security advisory telling people to "browse safe" wasn't quite enough. If you are using a Windows workstation, keep your eyes out for the patch tomorrow.