In an Investor Q&A, Nintendo President Satoru Iwata discussed the Backwards Compatibility regarding the Wii U console. Specifically the continuation of selling software for the Wii. He elaborates on the significance of giving the consumer a large library during a console transition phase, reducing the amount of devices on the T.V stand and capturing the consumers who never played Wii. There was no mention of the GameCube or GBA being re-released on Virtual Console. Both of which have been speculated to appear on the service sometime in the near future. You may read the entire O&A here