I think .net still has a very specific place in the world on internal intranet applications and tools. It's very easy to go in and make something good enough to provide the backbone web service layer between two departments, or to provide data entry and search services.
I don't think this advantage will go away overnight but at the same time the ease of entry and user friendliness of the open source tools is something that I've found Microsoft to be completely incapable of understanding. They/we would constantly talk about our superior tooling. But the fact that we required tooling at all when you could jump into roo or ror or cake or zf and issue a few commandline calls to produce 80 of the your site blows any of microsoft's tooling away.
Microsoft is fighting back and working to improve it's tooling. They have nice concept floating around to database versioning and javascript ide experiences, but in many ways they still seem to not get what the appeal of the open source competition is and i'm not completly sure if in the long run its an area they'll manage win back any mind share in.
