Some of you might have noticed that your Windows Explorer View is misbehaving in Office 365.
Chances are you are using ADFS to sign into Office 365? Then the problem is clear :-)

Windows Explorer will treat the request as a windows authenticated request, but... won't sign you in! Why? because it only forwards your windows credentials to the domain that belongs to your machine/network and not some random server on the internet. such as your office 365 tenant ending in sharepoint.com

the fix? Simple. use the same hack you use if your sharepoint intranet is on a different domain suffix as your primary domain. Add *.sharepoint.com to your AuthForwardServerList:

http://support.microsoft.com/kb/943280

Happy Single Sign On everybody!