Do the two GPUs work together?

I would like to know the answer to this as well. My first impression was "Yes", they could work together as a hybrid SLI. There has been absolutely no information on this however other than battery power improvements that result from turning the dedicated off and using the integrated. If this is the case, I think its a complete waste. You put in an extra more powerful graphics card and don't let them work together in SLI mode? Seems odd to me.

Bottom Line: I don't know and no one else apparently does either.

Sorry folks, the answer is a big no.

two vid cards redundancy is for power management coupled with application performance.

You can't SLI microprocessors that are not of the same speed and buffering capacities, and you definitely can't change anything about integrated + dedicated VRAM post facto.

Bottom line is this is for fanciful multipurpose optimization (yet silly enough that it takes extra space and weights more)

nope they dont work together. But isnt this something snow leopard will be able to do? I thought i remember reading that, making it the real reason apple would include 2

They can't both act as video drivers at the same time.

However, it is hypothesized that in Snow Leopard, Apple will find a way to use the GPUs as additional computer power for the machine. In that case, if you have them both on, you should be able to use one to drive the display, and the other to do compute-intensive work. 10.5 can't do that today, and it isn't clear exactly how it will be partitioned, but perhaps 10.6 will be able to do it. I believe this is going to be a key positive for 10.6. We'll have to see wehther Windows 7 or its successors will incorporate anything like this.

No according to nVidia, that feature is called Geforce boost and doesn't work on the 9600mGT
http://www.nvidia.com/object/hybridsli_notebook.html

The high-end/low-end 2 GPU configuration Apple worked on with NVIDA for the new MacBook is not something I find beneficial either for a gamer, an Artist or for those that work in broadcast or even film production. The reason for this is if both GPU were the same then the user could use them both in SLI mode when needed which would speed up rendering and take more workload off the CPU. Any person with basic computer knowledge should know they can extend a laptops power by turing off services they don't need at the time and lower the display lighting. This can already be done on current MacBook and MacBook Pro with out a need to have a lower end GPU. As an Artist my only wish is for Apple to fire the guy who thought this design was a brilliant idea and actually hire someone that knows what Artists, gamers and broadcast/film production users want and need in a mobile solution. In my case SLI NVIDIA or ATI GPU, Blu-Ray DVD RW drive, Intel Quad Core 64-bit CPU, 17" HD non-gloss display, Firewire and a 500 GB 7200 RPM shock resistant hard drive. If they can come up with that in the next 6 months then I'll be willing to spend my hard earned money on another MacBook Pro.