Some are (more or less) free, others are not. Rust simply gives you some great tools to make the choices yourself. The biggest win tends to be that you can get away without a GC, but still keep the guarantee that you're not leaking memory by forgetting to collect it.
To be fair, I think the way GP worded it might still be accurate; they said that you wouldn't leak by forgetting to collect it. I took that as a statement about not needing to manually free things than an assertion that Rust guarantees no memory leaks (which can still occur from things like reference cycles).
I too try (and sometimes fail) to be careful when talking about this. People get all hot and bothered when you go overboard :P It can be tempting to start explaining what an afine type system is, but that can hurt more than help.
