Funny you ask...
Last week I finished a prototype which produces 150w per channel stereo and can be bridged mono for 450w (8 ohms).
It uses a custom 1200w switching supply designed specifically for this purpose, and could be very small and light weight (8.5"w x 2.7"h x 10.5"d and around 8 lbs.).
We still have a lot of testing and refinement to do. If it meets our demands of performance & reliability, we may put them into production. If so, it would probably be ready around Jan 2011.
Understand that we build prototype products all the time, only about 1/3 make it to production. It has to be a great product and a good value for our customers...so we will see.