The App Store has had some minor changes with firmware 3.0 but the best one, I think, is the way screenshots are displayed. All you have to do is scroll down to the screenshots section and then just flick sideways to see more screenshots. Also, there is an additional option at the bottom of the app, the More tab. This is because another options screen has been added called Redeem. This used to be only in the iTunes app but now is in both. This way you can redeem promo codes for apps right in the App Store.
With the More tab, you can also tap edit in the top right and rearrange your tabs. If you have the Updates option under the More tab, it still shows a red numbered badge when you have updates.
You will also notice a View Account button at the bottom of most screens if you scroll all the way down. This lets you see your iTunes account information. You can actually update your account info on this screen like your method of payment or address.