AD PowerShell on Windows 2008/2003 - supposedly
As James pointed out recently the AD Web Service from Windows 2008 R2 has been released for Windows 2008 and Windows 2003 - see http://blogs.msdn.com/adpowershell/archive/2009/06/23/use-active-directory-powershell-to-manage-windows-2003-2008-dcs.aspx for details.
Having installed it there doesn’t appear to be any sign of the AD cmdlets or Provider. On this basis it is useless. If anyone knows different please let me know because I’ve looked in all the logical (and illogical) and I can’t find those cmdlets. The Windows 2008 R2 RSAT won’t install so that source doesn’t work.