Of the changes that didn't make the blog post (but is buried in the release notes) is that cargo-publish will now block until the publish process is complete.

Of the changes that didn't make the blog post (but is buried in the release notes) is that cargo-publish will now block until the publish process is complete. This affects you if you are releasing a series of crates in a row or released one crate and then immediately tried to use it in another. Before, it would break and you had to retry. Now it will just work. This was the original behavior but it was implemented server-side. Things were getting backed up, so they made server processing asynchronous which broke people's workflows. Tools like cargo-release compensated for that. With 1.66, we now have client-side blocking until the crate is published.