Ok, how did I manage to miss this?

I've been working on some PowerShell cmdlets, and I just recently migrated my dev laptop from XP Pro to WS08 x64 (so I can run Hyper-V, natch). All of sudden, my cmdlets weren't being registered, even though the build was working fine and installutil was running with no errors. A half hour of head scratching and a Google search later:

The version of the InstallUtil program that you must use varies depending on whether you are installing on a 32-bit or 64-bit platform.

To install 32-bit registry information, use: %systemroot%\Microsoft.NET\Framework\v2.0.50727\installutil.exe.

To install 64-bit registry information, use: %systemroot%\Microsoft.NET\Framework64\v2.0.50727\installutil.exe.

Jeez. I feel like going all Nancy Kerrigan on the Framework team: "Whhhhhyyyyyyyy"