Planet Planet doesn't appear to have been updated since 2006, and Planet Venus was most recently updated in 2011. Neither appears to be maintained in any way, though Venus has a variety of years-old pull requests currently open.
I don't think adding a Rust planet to Mozilla's planet instance (as suggested on IRC) would be the best solution, partly because it'd increase confusion about Moz "ownership" of the project and also because the configuration can only be edited by asking a human through Mozilla's support ticketing system.
If we get a Planet, I'll configure it so contributors can add blogs via pull request on GitHub. Before going any further, I'd like the community team to clarify what the guidelines for which blogs are suitable to add to the planet will be.