Thelatest beta of Ableton Liveadds a few neat features for Mac users.
AUv3 support in Ableton is BIG, musicianPynchon said in the Audiobus Forums.
It is also the only plugin key in supported by iOS and is very popular in iPad music apps.

Ableton
Well, technically, not much.
AUv3 plugins are just another kind of plugin.
The difference is that the music apps on iOS are a lot different.

you could mangle incoming audio on the fly, creating a performance as your go.
Its amazing with the touch screen, and theres nothing like it in Ableton.
Not all iOS plugins are available on the Mac.
The developer has to opt-in.
For the iPad, $10 is considered expensive for an app.
On the desktop, $150 for a plugin is normal.
Also, sometimes an app is just better on iOS.
Koala FX is one example.
Touching it is more fun than using knobs or a mouse.
Another example is ThumbJam, which lets you play realistic-sounding instruments via taps and swipes.
It would be utterly pointless on the Mac.
It’s already a place where people can get experimental, and now it can be even weirder.