The MSBuild team is looking for some feedback from the community to keep their "vision" for the next version of MSBuld aligned with their customers wants and needs.  They've got a blog post up here that asks for you, the MSBuild experts out there, to rank various potential new features they could work on.  Here are the various options (with fuller descriptions elided):

  1. Higher performance multiprocessor support...
  2. VC support...
  3. Support for other Microsoft project types that aren't yet in MSBuild format: Deployment/MSI (*.vdproj), SQL Reporting (*.rptproj), Biztalk (*.btproj), Prompt (*.prproj), etc...
  4. Conversion of Visual Studio solution files (*.sln)...
  5. Extensible up-to-date checking...
  6. Distributed build...
  7. Extensible re-usable inline tasks...
  8. Typing and scoping for items and properties.
  9. Extensible functions...
  10. An MSBuild debugger...
  11. Visualization for project and target dependencies...

Personally, my vote would be to spend $50 on getting the full solution/project system MSBuild compliant (#'s 2, 3, and 4), $40 on the debugger (#10), and $10 on the miscellaneous syntax improvements (#'s 8, 7, and 9 - in that order).  The rest of the features (improved multiprocessor support, distributed build, project/target dependency visualization) target what I would think would be a pretty small segment of the market, especially given the current lack of real VC support. 

But hey, what do I know!?  Go to the original post and share your priorities with the MSBuild team.