A bit late, but I was pre-occupied with a few things so it went under my radar.
This release brings some exciting features, such as automatic-sharding and replica-sets, which completes MangoDB’s Horizontal Scalability and High Availability to a complete solution. A finer control over consistency is also available now, with the w option, with which you can assert update propagation to a certain amount of servers (so if you use replica sets of 3 machines, you might want to set w=2 or even 3, depending on your consistency needs).
These features, along with the fsync option, makes MongoDB a legitimate solution for both high-scale distributed data stores, as well as for small, single machine scenarios. Everyone can enjoy the simplicity of this DB engine.
As for using MongoDB from .NET, I’m still undecided between mongo-csharp or NoRM. I also successfully used IronRuby with MongoMapper and Mongoid, so at least we have plenty of options at our disposal.