Definitely, and in fairness these are situations where there's a huge investment in MS technologies, with entire teams dedicated to supporting and maintaining the infrastructure. It isn't feasible to throw it all away without a serious commitment from the highest levels of the organization, and a multi-year, multi-million-dollar implementation plan to do so.

But at the team and individual developer levels I think there's lots of room for good open source solutions, and this option isn't always considered because developers are looking to MS for the next big thing.

I believe this is reflected in the certification programs too, because they don't focus as much on building a sound programming foundation as on making good Microsoft evangelists. From Microsoft's viewpoint, why not? But it's that divergence again from the company's perspective.