Windows XP Service Pack 3
As reported by ComputerWorld, the latest Service Pack for Windows XP, SP3, is finally available via the MSDN and TechNet download sites.
This is only for the 32-bit version of XP, btw. Users of XP x64 will need to wait for Service Pack 3 for Windows Server 2003 in order to get an update, as the 64-bit version of XP (non-Itanium version) is based on the Windows 2003 code-base.
I would expect this to be the last major software update for the 32-bit Windows XP family, given the Windows support lifecycle, and Microsoft's focus on Vista. That said, the arrival of this service pack is not without some controversy -- especially for the people who don't like Vista.