In iOS 5.1, Apple added a new feature to Mobile Safari. You can simply tap and hold on the New Page icon for a list of your recently closed tabs. This feature is similar to Chrome's CMD-Shift-T feature and desktop Safari's CMD-Z feature to open up tabs you may have accidentally closed. This feature is very helpful and it is now on iOS 5.1!
Hope this tip helped you! Please leave any questions, comments, or concerns in the comments below!