This one got sidetracked quite a bit. I expected more discussion about trade-offs of the implementation: building upon Dictionary vs reimplementing the hash table, different types of value collections (list, set), usage of value types to avoid garbage, introduction of a new IMultiDictionary/IReadOnlyMultiDictionary interface, etc. Also, I don't know if I missed the secret signal that prevented Charles from asking what the second collection being worked on is, but it would have been nice to know!
The F# information rich programming concept was kind of an eye opener for me. It makes a lot of sense to strongly type external data sources in this way. I find it very interesting to watch where F# is going, even though I don't use it myself.
I also want to +1 Luna's comment about the contrived C# code. A dishonest comparison like this is far from the best way to win over new developers. I'm sure you can do better.
I've been using VS11 beta since it came out and, although my initial reaction to the new theme was to recoil, I've gotten used to it after a day or two. I wouldn't say it's better than 2010 but it's good enough. I do think that icons are more difficult to recognize, but I make a point of minimizing mouse usage anyways. There's also a consistency problem when you have extensions and they provide colorful icon, but I guess that's unavoidable.
So yeah, I don't understand why the change was made, but it's okay and I'm not complaining. I think that the various IDE improvements outweight the minor discomfort caused by the theme change.