This is apparently old news, but its worth repeating as it came out of a presentation gave earlier today at WinHEC. According to an earlier report,

As part of its commitment to 64-bit computing, Microsoft has been delivering products that are optimized for 64-bit, including the newly released SQL Server 2005, Visual Studio 2005 and Virtual Server 2005 R2. To help customers take full advantage of the power of 64-bit computing, products including Microsoft Exchange Server “12,” Windows Compute Cluster Server 2003, Windows Server “Longhorn” Small Business Server, and Microsoft’s infrastructure solution for midsize businesses, code-named “Centro,” will be exclusively 64-bit and optimized for x64 hardware. In a future update release to Microsoft’s upcoming Windows Server “Longhorn” operating system, code-named Windows Server “Longhorn” R2, customers will see the complete transition to 64-bit-only hardware, while still benefiting from 32-bit and 64-bit application compatibility. For the highest-scale application and database workloads, Windows Server on 64-bit Itanium-based systems will continue to be the premier choice for customers for years to come."

32-bit resistance is futile.

The revisiting of this topic comes out of a little brouhaha from WinHEC. There it was mistakenly reported that Vista would be the last 32-bit client O/S as well from Microsoft. According to the post...