Is it possible to create a SSO plugin using WordPress.com accounts?

Just lost a post :/ — posting something you already posted a second time sucks. 🙁

Anyways, my idea is this: Is it possible for WordPress.com and WordPress.org to “team up” so that someone who is an “Author” (or above) on a self-hosted WP.org site/network could somehow authenticate themselves, and then post simply by being logged in @ WP.com?

It’s certainly possible that I am missing something quite obvious — it was just a random idea (more or less).

Or perhaps this is already possible (?) — if not, what do you think of the idea? Possible? Impossible? Useless? Useful? …?

ps: I’m aware there are “solutions” via Janrain (or something like that), but I have tried that before, and I find it “too complicated” O_O — I mean something relatively “quick and easy”;)