While gamers have been waiting for an official GBA VC for the Nintendo 3DS for years since the Ambassador Program was instituted, the Wii U is actually the one getting it instead. With little warning, it has been announced that the GBA VC will be arriving in Europe for the Wii U on April 3.
The first GBA game to hit the WII U VC will be the classic Advance Wars next Thursday in Europe. Advance Wars is a very fun RTS game that helped to define the early days of the Game Boy Advance, and I know I will be getting this one once it hits the US, hopefully sooner rather than later.