Bye Bye 32-bit
It's true, Microsoft has announced that Windows Server 2008 will be the last 32-bit server produced. Starting then, all server based operating systems will only support the 64-bit architecture, including x64 / EMT64, and IA64.
Microsoft has been pushing the 64-bit platform lately, with the Groove 2007 Server being only commercially available on the 64-bit architecture, as well as the Exchange Server 2007. While 32-bit versions are available, they intention is for evaluation only.
What does this mean for developers?
For Developers of the .NET Framework, not at lot. If you're using the .NET Framework 1.1, you might have some issues. For .NET 1.1 to work properly, IIS needs to run in WOW, and as 64-bit becomes more mainstream, server administrators will be hesitant to enable WOW on IIS for a single application.
For .NET 2.0 and up (3.5, and future), these support both 32-bit and 64-bit, so more often than not, it doesn't require a single change to code.
We're not too far away from 32-bit becoming legacy.