One of my favorite features of the iPhone 2.0 is a little bit of spit and polish that's not getting much press (I haven't seen anyone else mention it, actually).
Previously, entering passwords on the iPhone was always a super pain in the butt. It was too easy to mistype something, and you couldn't tell that you'd made a mistake, since the password was all dots.
Now, the password fields dot-out all the letters except the last one, letting you see the last letter you typed. Yes, that sacrifices a bit of security, but if someone is peering that closely over your shoulder, they can probably see what you're typing anyway. And somehow, just being able to see the last letter makes it so much easier to type in my passwords correctly.
Oh, there are a lot of more-obvious features that I could also rave about, but I think the new password fields deserve a little love.