Hello Ido,
Uhuru is a .NET version that extends Cloud Foundry just like the Iron Foundry Project (which is started by Tier 3).
I'm not 100% sure what Uhuru's plan is with the IIS version differences, which shouldn't be tied to the version of .NET application deployed via Cloud Foundry.
The run times and framework versions should boil down tot he runtime versions of .NET. The Iron Foundry projects supports projects that run against the 2.0 CLR and the 4.0, in other words, pretty much every single .NET project that exists. The IIS Version is pretty much dictated by the latest version of Windows Server. With the Iron Foundry add ons Windows Server 2008 (and soon to be 2012) should be available and depending on which provider makes which OS available you'll have various capabilities around IIS.
I hope that helps a little. If you have any other questions just ping us here in the group. Sorry about the late response, it's been a bit hectic lately.
Cheers,
Adron Hall