This was just posted today. I've tried it for my .CR2 files and it works great. Can see the thumbnails right in Windows. Beware, 47MB download!!
http://www.microsoft.com/downloads/details.aspx?FamilyID=d48e808e-b10d-4ce4-a141-5866fd4a3286&DisplayLang=en
http://www.microsoft.com/downloads/details.aspx?FamilyID=d48e808e-b10d-4ce4-a141-5866fd4a3286&DisplayLang=en