I've recently seen a lot of job postings looking for .net developers. My career was as a software developer, but I had never heard of anyone calling themselves a .net developer. So I did some searching around and came upon the same question discussed in some forums. Here's one comment (not by me) that I think should be read by every HR department and anyone else posting for .net developers:
Though I consider myself a .NET developer, I don't prefer calling it that way. c# developer sounds much better and is a much clearer message: it says that I understand both C# and .NET (because C# and .NET are tied together). I could call myself a VB.NET developer, same story there.
What is a .NET developer? I don't know, because you cannot develop with .NET, if develop is a synonym for programming. .NET is the environment, the libraries, the languages, the CLR, the CLI, JIT, the LR, the BCL, the IDE and the IL. I find it a poor job description, but it may also mean that they don't really care: either you are an F#, a C#, an IronPython or a VB.NET developer, they're all implicitly and secretly .NET developers.