Java redefined the term MVC a long time after Smalltalk originally defined the term in the 70's. Rails didn't redefine the term, it much later copied the (poorly) redefined term from Java and tweaked it a little. Smalltalk MVC and Java/Rails MVC are EXTREMELY different. Java and Ruby's MVC are quite similar (and loosely based on a superficial misunderstanding Smalltalk's MVC).
If you would like a book, I cannot recommend "The Art of Prolog" by Sterling and Shapiro enough. It gives a very understandable introduction to the language and is focused on teaching you how to approach different problem spaces while "thinking" in Prolog.
We haven't changed course. As Ixiaus mentions, there are several chicken and egg problems involved around the 'semantic web'.
We're starting with specific content publishers right now that use a combination of our web-based editor (which looks like a normal editor, but allows structured content creation) and APIs to get information in to Silk. This allows them to create sites where people can play around with the structured data, create visualizations, etc.
Longer-term, we'll open up the editor to the general public. Our goal is to do to structured content what Blogger and Wordpress did to weblogs.
Regardless of XCode 4 free or paid, it would be nice to have a compiler separate from XCode. Installing the whole IDE you never use has always seemed like an overkill.
Also known as MVC before Rails decided to redefine the term.