The core team has been working for some time to hammer out a policy for Rust's trademarks -- which are distinct from the copyright policy surrounding the code and logos. In particular, while copyright governs how an artifact can be copied and modified, trademark talks about ways that a particular "brand" can be applied. (Look here if you want a long read about open source and trademarks.)
You can read our policy here.
Note, the website's new invalidation system may mean you see a stale, misformatted copy of this page. Hopefully the final version will hit all of the caches soon! You can also read directly at prev.rust-lang.org/legal.md at master · rust-lang/prev.rust-lang.org · GitHub
The basic news here is that we are adopting a pretty liberal stance around Rust's trademarks, allowing our logos and names to be applied, even in modified form, in many contexts -- so long as the use does not imply official endorsement by or affiliation with the Rust project. (Commercial uses need to check in so we can confirm this is the case, before money is ever involved.)
That's the TL;DR, but please read the full policy to understand the role that trademark plays, and the nuances of our approach.