Managed code makes it very easy to version your applications... Because we have gotten rid of the global registration (at least for apps) it is much easier to write a side by side application... That said there has been some internal folk asking about how to how to handle external resources (such as reg keys, file paths etc)... We dug up this whitepaper to address that and I thought I'd share it...

How To Build and Service Isolated Applications and Side-by-Side Assemblies for Windows XP