The foundation is now nine months old, but I don't see any announcement on its website saying that the trademarks have been transferred.
The Rust website [1] says that the Rust trademark is still owned by the Mozilla Foundation.
The README in Rust's git repository [2] says it's owned by the Rust Foundation.
I am distinctly unimpressed by the foundation's communication skills so far.
[1] https://www.rust-lang.org/policies/media-guide [2] https://github.com/rust-lang/rust