Hammett, founder of Castle, the father of MonoRail, went to Redmond invited by the ASP.NET MVC team, to review the new framework, and give his opinion based on his experience having built a similar framework.

You can have a look at the blog post where he wrote his opinions, but I'd like to quote here the ones I feel are the most impressive:

[...] surprisingly - at least to me - is how MS is approaching this framework. They are not in a rush, they are more concerned about getting it right than getting it done fast. My overall impression is that they are really crafting a framework.

[...] for folks with lot of expectations, the CTP might be a turn off. That’s because what you’re going to see is a very small framework, with a lot to be done to be useful.

Which means that when it comes out it will be a very well crafted framework, not just something rushed to ride wave of the ALT.NET movement and trend. So the CTP that will come out in the next months will be just an overview of what we will be seeing in the future, but probably not really useful.

MonoRail 2.0 is pending their implementation. If the final MS MVC rocks, and provides so many things, I’d vote for forget the MR 2. If the final MS MVC has clearly something lacking, MR 2 could reuse the infrastructure and provide some nice extensions.

That's a really good approach by Hammett: no point building the exact same thing if it works.