Windows Server 2008 R2 has TaskBar Api as well

More info at:

http://msdn.microsoft.com/en-us/library/windows/desktop/ms724832%28v=vs.85%29.aspx

Versions

Windows 8               6.2
Windows Server 2012     6.2
Windows 7               6.1  *
Windows Server 2008 R2  6.1  *
Windows Server 2008     6.0
Windows Vista           6.0