Yesterday, one of the attendees from the Virtualization events asked this question which I though would be worthwhile to share:

For a simple .NET application like this, would we need different applications when running on 64 vs. 32 bit hosts?

Before answering, please allow me to elaborate more on where the question is going.  Virtual Server has a COM API that allows it to be managed by applications and scripts.  Virtual Server R2 SP1 Beta 2 (phew) comes in two flavors: 32-bit and 64-bit.  The owner of the question wondered if you could manipulate a 64-bit instance of Virtual Server using a 32-bit application (or vice-versa).

Ok, now that the question is (hopefully) a bit clearer, the answer to the question is no, you do not need to have a different version for accessing Virtual Server from an application regardless of its bit-architecture.  Why?  Virtual Server's COM API is accessed by an out-of-process COM library, which means that everything is done by means of RPC.  When two applications are communicating with each other by means of RPC, the 1st commandment of 64-bit is not broken (thou shall not run 32-bit and 64-bit code within the same process space).