kibwen already posted more details about @ in Rust 0.10, but the short of it is, @ still exists but is gated behind a feature flag. Code that uses it is still being updated. The functionally equivalent replacement is std::gc::Gc, but you should consider std::rc::Rc for reference counting instead (which supports weak references).
Ah, that's a shame. I actually just mentioned the tutorial as an awesome resource in another comment.
Maybe my understanding of the Rust language isn't as good as I thought it was, as most of it comes from reading the tutorial and the related guides linked at the end.
I'm a big fan of high quality documentation, and I assumed since the current tutorial was so well written, it was being handled actively already. This is actually one area I would love to step up and help Rust with. I've previously gone so far as to read some of the compiler implementation, but my experience with programming languages is still stuck in the interpreters stage, so it didn't get very far.
The guys on #rust-internals are super nice and can help you a great deal if you are interested. But tbh, we really need more contributions with respect to documentation. Again #rust-internals can guide you if you are interested in lending a hand.