before anyone blows a gasket... this is NOT sync as most people think,

but a way to sync you crates and library between 2 devices.
(ie make the changes on your ipad in the library management software match the library in scratch live and vice versa)

how it came about.
Im traveling more and more and with years of collecting music/videos im constantly taking 15 minutes and just deleting tracks, adding notes to files, changing genres...
I guess you could call it, "offline library maintenance" for lack of better terms.
but this involves pulling out my gig computer, pulling out my external harddrive.
(which i dont always have with me, or its in the overhead bin, the trunk, or im on the train and just have my ipad with me)

much like most programs that work between the ios's via a daemon on sync program
you can make changes on the ipad to the program, sync them over the wifi and the changes would be reflected on the mac

obviously music playback would be pretty much impossible (unless perhaps you are synced between devices, or could remote login to your gig-machine from the Ipad)
but this wouldnt be for playback.
but more for previewing, setting crew points, making grid adjustments.

this way you could sit on the plane, bus, train, couch and do the most simple library management via your ipad.... get home, sync the device, and all the garbage is deleted, all your notes are made. you could even build a playlist in the cab on the way to the gig, then review it after on the way home.

this is just realtime spit balling ideas.
but im not one that uses his gig-machine for anything but spinning,
but arguabbaly you could even allow the sync not only from a ipad, but sat a 13" macbook air or something via the remote login/sync of the library.