Holy Crap! In tiger u can add soundflower's 16CH interface into an aggregate device with your other audio interfaces for instant busses between tracks in your DAW and between applications! Just like Jack, except maybe requiring less system resources to run, and no configuration beforehand. Maybe more stable too - we'll have to see. Just make sure to not make any feedback loops by accident!
This really helps in Logic, where the only way normally to hard-record stuff on another track is to bounce and reimport. This also might be kickin' for Logic <=> MaxMSP connections!