I think it's really great that they're building an MVC product for ASP.NET at Microsoft! I think it has the possibility to bring a lot of PHP, Python and Ruby guys onto the platform.
But it's not ready to use yet so I'm going to use CodeIgniter. Sure people are out there coding with the beta, or I could even use plain ol' Web Forms, but long story short: it isn't ready. It's going to be awesome when it's done, it's awesome now, but every new beta brings out breaking changes.
So even though it makes me sad to leave my beloved C# for one site, I'm gonna have to stick with PHP for this one.