I've been checking here in "beta you than me" for 8320 4.5 info, seemed logical, don't you think?

However, over in "general 8300 series discussion - curve" there's a post now several weeks old regarding the release by orange uk of 4.5.0.52 for the 8320, with accompanying download links from blackberry.com.

There's carrier released versions of OS 4.5, and there's also newer beta versions which haven't been released.

This forum area discusses the unreleased versions which are still in beta.

There's not just one OS 4.5. It's still largely a work-in-progress.

Yep. As you said, it's been there for a few weeks now.