I was pleasantly surprised to see a spell check feature inside the Appstore on my iPhone 3.0. While searching for any app in the AppStore on OS 2.x, a spelling mistake shows us similar spelled apps, but here it asks you if you actually meant some other spelling (like in search engines).
iPhone OS 3 has hundreds of bug fixes and features added, not all of them have been listed by us. Hope to stumble upon more such new features.