A friend of mine recommended that I read up on Linear types and associated work. I might take the time to discuss those type systems as they relate to Rust as a follow up. At that point I would address borrowed pointers.
If you need any help with that, don't be shy to jump on #rust on irc.mozilla.org. The team would be happy to answer any questions you may have along the way.
It's very good! The only minor style issue is that `io::println` is deprecated in favor of just `println`. Everyone keeps getting this wrong, it's already gotten me once today... it would be nice to start getting the word out. :)