The A4 absolutely offers "active lane assist" (steering) as well as "adaptive cruise control with stop and go" (automatic throttle and braking, all the way down to stopping in traffic).
I don't think it's quite as autonomous as Cruise - as noted by others in the thread, Cruise seems to be trying to reach a somewhat scary "good enough that you could read a book but please pay attention because it doesn't work just right yet" plateau, while the Audi system is simply supposed to be a gentle helper of sorts.
But the Audi system also works on any highway rather than just pre-mapped areas, and is (for better or for worse) integrated with OEM brake and steering actuators and the car's throttle-by-wire system rather than relying on retrofitted physical systems.
