Apple has released iCloud for Windows 2.0, with compatibility for iOS 6 and not a whole lot else. The most notable update is improved support for Photo Stream. Users can now access streams that have been shared by other iCloud users.
Windows users will also find a Photo Stream link in Windows Explorer for easy access. That's really the only major addition here. There are also several bug fixes and the like. If you're a Windows-toting iCloud customer, go and get it.