I've set up a 64-bit TFS 2008 build server with Sharepoint, continuous integration and out-of-the-box MSTest. Unit tests for plain business logic classes run just fine and test results are published into TFS. However, any test that uses Sharepoint's API fails horribly, SPFarm.Local returning null and so on. Is there a way to fix this?

The tests run fine in an otherwise identical 32-bit development environment (Windows Server 2008 under Hyper-V, Sharepoint patched up to June 2009 cumulative update) from both Visual Studio and command line, so the problem is not about improper use of SPContext.Current or any other part of the API that needs to be run in a web server context. I've ruled out permissions issues, because the build agent account can deploy the solution and create site collections just fine with stsadm. The next culprit could be that the unit tests were being run with a 32-bit process, which couldn't access the 64-bit Sharepoint API properly. I tried a workaround, but it has the side effect of disabling TFS support in MSTest.

Do I have to wait for 2010 versions of MS tools (and hope for the best) or is there a third-party test framework available that runs natively in 64 bit and can publish test results into TFS 2008?