I find F# very tempting as a gateway into .NET. Anyone used it with MVC?
It's fairly straight forward to use with MVC, though it's less than ideal. You basically need to have a C# MVC project that referneces your F# projects (these would contain your controllers etc.)
There's also the question of Razor supporting F#, which is not yet there. I remember somebody spiking some code for that, not sure if it's usable.
You can still write all your controllers in F#; but if your front-end is C#(razor), and if your data access is in L2S or EF, then F# feels like added baggage. Still could be useful in some occasions.