Not sure I understand. Bun's changes are merged on the dev branch and available for use, no?

EDIT: Oh, look, blog post on the front page now.

https://bun.com/blog/bun-in-rust

> Bun v1.3.14 was the last version of Bun written in Zig. Bun v1.4.0 will be the first version of Bun written in Rust. It's available in canary now.

So, yes, it seems it was definitely more than a "marketing stunt" and it's broadly available and slated to be the production release soon.