Saw this question here : What Great .NET Developers Ought To Know (More .NET Interview Questions)
It will show processes that have loaded modules (usaully .DLL files) hosting the .NET runtime. The same technique can be used to search for other DLLs that have been loaded.
On a related note, Process Explorer is a Microsoft task manager replacement that will show .NET processes highlighted. I cannot recommend it enough. It is well worth investigating along with the rest of the Sysinternals Suite.