Can I migrate Java-language source code to J# and access it from, say, C# or Visual Basic .NET?

Yes; J# compiles to Microsoft intermediate language (MSIL) and any CLS-compliant language (such as C# or Visual Basic .NET) can utilize code generated by J#. Many customers are using J# to bring Java-language business logic or libraries over to the .NET Framework so that they can be used from their other applications. Likewise, J# can access functionality from assemblies created in C# and other languages.