Gmail's mobile Web app for iOS added a feature first available in Tweetie, which is now the official Twitter client for iPhone and iPad. Instead of clicking a button to refresh the list of messages, you simply pull down the list and wait to see the new messages. It's a really intuitive way to update a list and many mobile apps started to use it.
"One thing that's cool about Tweetie 2 is the fresh paradigm to refreshing the contents of a table view. Up until now we had been looking for space to mount a reload button on, sometimes having to resort to adding an extra tool bar for just one view so that you can have enough space. Now if you have a tableview that it sorted reverse chronologically, then you have a natural urge to make new items appear at the top by pulling down the table with extra force," suggested Oliver Drobnik back in 2009, when Tweetie added this feature, which is now available in mobile Gmail.