link emulators on desktop

Doug and Nick were in a side discussion the other day about desktop
modelling tools that could give the marketplace team a better feel for cell
networks.. we talked about netem and dummynet..

I just saw this - a pretty slick UI in os x 10.7.. anybody used it? (I'm
not using that platform)  - does it do latency well? does it do variability
well in the mobile profiles?

http://mattgemmell.com/network-link-conditioner-in-lion/