So, the Main Scala Website has a "tour" of the features of Scala. I liked the idea, but found a lot of the examples and descriptions a bit terse and uninspiring (some of them are downright confusing). However, I really wanted to learn about these features. So, I set about understanding each feature, trying to answer the question "What problem does this solve?". The results are here at www.naildrivin5.com/scalatour. This site was constructed using my homebrew wiki software, Halen (which I created to test out my Gliffy Ruby client).
It was a fun experience. As someone coming from Java application development (and who knows enough Ruby to feel some pain in Java), I tried hard to map the features to real-world problems a "blue-collar developer" might be facing. A lot of Scala enthusiasts seem to be functional programming nerds, and I know FP can turn a lot of people off. I think Scala is a great way to learn and appreciate functional programming without having to swallow a huge amount of info at once. So, I figured approaching Scala's features from a different angle would be useful.
I did have to supplement my learning with info from Odersky's awesome Programming Scala book, but most of what I learned, I learned by playing around with code; all the code on the site should compile and run (at least in Scala 2.7.x). The coolest thing was that by "touring" all of Scala's (often weird) features, I got a good feel for how they all fit together. The language feels like a very elaborate Rube-Goldberg Machine that ends up being rather elegant. I feel that instead of casting Scala as a functional language, or a hybrid language, I would say that Scala is "static typing done right (or as right as is possible)".
The way Scala allows for duck typing, for example, is really cool, and something I think Ruby code could benefit from. Stuff like type variance is pretty heavy stuff, but when you dig into, and understand how functions are implemented, it ends up making some sense. I even found a "real world" use for explictly-typed self-references, which I thought was actually a sick joke for a while :) Anyway, I hope that what I've learned doing this will be helpful to others.