OMG!!! This is absolutely sweet! Granted, I haven't used it, but the prospect is awesome. With ILMerge a developer can combine multiple .NET assemblies into one. I guess the main reason I'm so excited by this is because I've done a lot of work with reuse libraries. I tend to break those out into core, web forms, windows forms, web services, and security libraries (among others) similar to how .NET is broken up. Due to this, people may have to copy 4 or 5 assemblies just to get the features they want. With ILMerge, they can all be managed together (since they're all part of one repository, anyway). So, by using ILMerge, developers have the choice to have one or five assemblies, depending on the capabilities they need to implement.
The only thing I wonder is how this might effect internal code (code that can be only accessed within the assembly). I'm sure I'll get a chance to test it out sooner or later. I honestly can't wait!