Just a place to share what people like about boo.
....Boo takes what's best about Ruby (heavy emphasis on closures/blocks), Python (indent-based scoping, first class functions), and C# (static typing, properties, annotations, "using", p/invoke, .NET native), and one-ups them with type inference. It really does provide the best of both static and dynamic typing; there is NO compromise here as far as I can tell.
As a bonus, the tool support is already very good. As with any self-respecting scripting language, it includes an interactive interpreter. (Boo scripts can be interpreted or compiled.) The Visual Studio .NET debugger already works with Boo, and if you write your Boo code in SharpDevelop (a free IDE for .NET platform) you can get code completion, syntax highlighting, code folding, etc. And since it's all statically typed, there is hope for IntelliJ-like refactoring tools, although I don't think any exist yet.
Bottom line, I think any Python, Ruby, or Groovy fan should take a long, hard look at Boo. You will find a whole lot to like.