There’s also a bunch of other new APIs, the most exciting being the Omnibox API. Imagine Chrome’s built-in search engines (type ‘Amazon’, then a space, and then a book name — it searches Amazon!), but with extension access. Type the name of an extension into the Omnibox, and then any further input is redirected to the extension. Actually, having said this is an exciting addition, I’m really not sure what an extension would do with it… Perhaps something Ubiquity-esque?
Oh, and if you make an extension (featuring the new APIs? It’s not clear), let Google know and they might send you a free Chrome hoodie! Hooray.