Double click the home button so you can multi task, try it when your in a game or something...
Keep your finger on an app on the home screen and the ones you can move and "file" will have an X, drag one of those over a similer type, like angry birds over sheep launcher and it will create a file, then drag your other game apps onto the file.
If you get an email with a date in it, it will underline and when you click it it will take you too a calander entry..
Not sure if I like the message grouping and the one inbox (and that you cant turn it off!!) but as thats how Outlook 2010 has gone I guess it unifies it slightly?