Following yesterday's release of the GarageBand update, and the first sale on Audiobus, it has shot up to #1 in the iPad Music category on the US iTunes! This is quite an accomplishment, and one of the few times GarageBand has ever been unseated from the #1 position.
I have to imagine nearly everyone reading this site has already bought it, but if you haven't, this is the time to do so! This is the first and potentially only time it will be on sale.
For all you new Audiobus owners, The Sound Test Room has posted a detailed starter guide!