I haven't developed a production app with MVC 2 yet but I've tested it for use in my organization and I've played around with RoR. Given that experience I'd put forth the following points...
Pros:
1. Despite what RoR fans claim I think you can get things done faster in ASP.NET MVC 2 (if you use Visual Studio). All the usability enhancements combined with technology like WCF simply help you get things done faster (though there's a down side to this advantage in the cons)
2. On the above note I still think C# is a vastly superior language especially now that it's essentially "borrowed" the best parts of Python
Cons:
1. The main reason to go with a MVC framework is ease of testing and the RoR community is far more robust and hence offers far more testing options
2. (Related to Pros #1) Using Microsoft technology like WCF creates performance woes. I would question using it on a really high performance site
3. You really need to buy Microsoft servers. I haven't even tested MVC 2 on Mono but MVC 1 was spotty and not officially supported
4. Support is minimal on the Internet. Again this boils down to there being far, far more Ruby developers (Let's face it ASP.NET MVC is a subset of the already smaller ASP.NET developer community)
I don't know if that helps but those are my initial thoughts.