ZERT has announced the availability of a temporary patch for the VML zero day exploit first discovered in the wild on Monday by Sunbelt researchers.
ZERT page here. Download link here. All standard disclaimer apply (use this software at your own risk, etc.).
eWeek story here.
However, remember that an effective mitigation that does not involve installing a software patch is to simply unregister the VML dll.
Alex Eckelberry