When I lived in Seattle, there was a good community of C# people for freelance work. I always wished for "C# on Rails", basically a Rails-like framework built on C# with convention, migrations, a reasonable package management solution (e.g. bundler), a mature approach to test, and a deployment system that didn't take 30 minutes to spin up a VM (Azure).
AppHarbor, you guys are bringing this one step closer to existing; great job.
When was the last time you checked in on C# land? It's getting a lot better lately.
ASP.NET MVC with Razor, Nuget, and the JUnit/NUnit-like test framework in Visual Studio are all in that line of thought. For something Active Record-like, historically more mature--and somewhat less ponderous--alternatives to EF and LINQ2SQL include NHibernate (FluentNHibernate is nice) and other approaches like Simple.Data, PetaPoco, etc.
Oh yeah, migrations have been notably absent, although I've tried a few like FluentMigrations, which is nice but "out of process" enough that I find it terribly easy to neglect.
This looks very promising. I've created my own lightweight system for automatic schema alterations and I can't imagine going back to working without it.
This could pretty much be a drop-in replacement for what I've done. Nice.
I do have a question though. I'm a .Net guy who has only worked with self hosted systems and Azure and I've always wondered how the latency affects people who build serious system using the add-ons provided. I just can't imagine it performing well without knowing where exactly your RabbitMQ(CloudAMQP), MongoDB(MongoHQ), and Memcache type services are hosted. They could be sitting in the next rack to you or in a completely different part of the country (in theory).
AppHarbor, you guys are bringing this one step closer to existing; great job.