An effort is already underway. Thankfully we have until the end of May to get this to a usable, somewhat mature state. RedGate's handling of this situation has lit a fire under me and a few other developers, and we're committed to releasing a free, open source competitor, and replacement, for Reflector.
There are some outstanding open source .NET libraries that blow away what you can get in Java. Likewise, some COTS .NET libraries blow away equivalent Java libraries (e.g., for unit testing and inversion of control, query-driven source code analysis, etc.).
But comparing .NET to anything other than Mono is apples to oranges.
