I came across the Ur/Web project during my search for web frameworks for Haskell-like languages. It looks like a very interesting project done by one person.
Basically, it is a domain-specific purely functional language for web programming, taking the best of ML and Haskell. The syntax is ML, but there are type classes and monad from Haskell, and it's strictly evaluated. Server-side is compiled to native code, client to Javascript. See the slides and FAQ page for other advertised advantages.
Looking at the demos and their source code, I think the project is very promising. The latest version is something 20110123, so it seems to be under active development at this time.
Has anybody here had any further experience with it? Are there problems/annoyances compared to Haskell, apart from ML's slightly more verbose syntax?