Okay...here's a handy tool. Now that we're releasing Community Technology Previews (CTPs) so frequently, it can be difficult (even for us Microsofties) to track which version of a product works with which version of the .NET Framework. The Channel 9 CTP Madness tool reports the versions that appear to be running on your current machine (via browsercaps) and shows which products are compatible. The tool relies on a simple BuildData.xml file that could easily be used to build a new frontend for the data. Special thanks to Brad Abrams, Jason Sutherland, and Charles Torre for making this available.