Moq has already been created...
http://rubygems.org/gems/moq
It's totally up to you whether to ILMerge or not. I like the usage of ILMerge as it allows your dll to use a certain version of a component while I as a developer can use a different version of that same component.
That said, there are good reasons to just point to a dependency. I subscribe to what makes the most sense for you. If you are a contributor, and you want to ILMerge, then by all means. If it's not your project, go with what the intent of the release was. In other words, when you download the release, if it is not ILMerged, I would suggest not ILMerging it.