Happy iPhone OS 4.0 day everyone! A potentially big day for the fanboys, you'll want to start off with the Gizmodo iPhone OS 4 Live Coverage, Gdgt, Engadget (announcement, liveblog), or the various others in the news.
Wonder what will be coming.... there haven't been any rumors before the announcement (other than speculation that's been going on since OS3.0), but since the announcement lots of people have chimed in with their wishlists.... better home screen, multitasking (or some Apple-y way of doing it within the paradigm of the iPhone/iPad and not turning it into a desktop OS), and more. Boy Genius Report has a nice rumor roundup. Of course, lets not forget Twitter.