Yesterday I was in the 5th Avenue Apple Store and they had a GarageBand demo going on. The presenter was had his Mac with two 30" displays hooked up to it for everyone else to see.
As you can see in the photo I took, the menubar was about half an inch and GarageBand's buttons were huge, but there was no pixellation at all.
The Dock was the only other thing visible on the screen but it wasn't enlarged.
Has anyone tried GarageBand using Resolution Independence?