Now a days .Net is run in multiple platforms,like linux ,Mac os etc.
but mono is not fully platform independent ,Because to deploy .NET in another OS required
third party software.so it is not like java platform independent.
Mono is running in different platform ,because of JIT is there in different os.
Mono is not fully success in moonlight(silver light in .NET) .Not only Research is going on.
Mono uses XSP2 server or apache . some of the big companies are using this project,Some of the robotic project are also running on mono.
For more details http://www.mono-project.com/Main_Page.