So when RB2 comes out, it is no mystery that you will be able to transfer all of your RB1 songs onto the new game. Well they just started to talk about how this will be done. The only thing that will suck is that it will cost you a small amount of money to do so. How much, well read on.
When the game launches, a new patch for RB1 will be released out adding an "Export" option to the menu. When you click on this, it will prompt you for a password. This password will be included in the case for RB2. Once that is entered, you will then be asked to pay a small fee. Reports state it won't be over $5 USD, but we'll see. Then it will copy all of the game data to your system just like the DLC you buy every week. So far this is only reported for the XBox version of the game, but it will most likely be the same way on the other systems as well. Unless Sony and Nintendo try to cut some deal to alleviate this small burden, but who knows.