Hello. Just a though:
How about playing movies from an iPod connected to the 770/800
by utilizing the power of the CPUs of BOTH machines?

It is clear that the ARM CPU even with a help of the DSP is not powerful enough
to play movies in a resolution comparable to the resolution offered by the LCD
(800x480!!!). (no offend against the mplayer guys!!! i know they do their best)

so i thought, how about
-storing a movie on an iPod
-putting the 770 into host mode, injecting 5V into the USB link
-mounting the ipod, establishing a connection
-doing some pre-un-compression of a video stored on an iPod
by the internal CPU of the ipod
-sending the semi-uncompressed thing through the USB link,
-doing the rest of the uncompression on the 770/800 devices
-displaying the video on the device.

Pros:
- more CPUs involved
- more storage place for the video (80GB recently)
- better display then on the iPod (320x240 recently)
- much better quality then recently on a stand-alone iPod or 770/800

Cons:
- need to charge both, iPod and 770/800
- need to inject some Voltage into the USB
(could be stelaled from the pins of new iPods)
- need for a SW for both, the iPod and the 770

I can provide USB-2-USB cables on request, plan to try the 5V output straight from the iPod.
A nice page for iPod coding: http://www.ipodlinux.org
And an overview of the iPod CPUs: http://ipodlinux.org/Generations

If you are going to go that far why even use the tablet's cpu at all? Why not use just the ipod cpu to decode and use the tablet as more or less just a display? But then you might run into bandwidth problems. How much bandwidth can an ipod or a tablet handle coming in or out over usb? The ipod has tv out, if you could figure out how to send that signal into the tablet and get the tablet to accept it as the video and audio stream maybe?

I see your point.
But I am afraid that the iPod CPU is simply not enough to uncompress
DivX videos that are of far better resolution then the supported 240x320..
(The main idea was to take a video, copy it to the iPod, connect your 770 and press
Play without any conversion for 770/iPod -supported format)

Ok, TV-out of the iPod: I am afraid we would need an external Audio/Video digitizer
attached to the 770 USB port with quite a high Ampere consumption (the Analogue-> Digital conversion should happen in THAT usb-converter...)
So, I personally do not really see that option.

USB-speed:
http://www.everythingusb.com/usb2/faq.htm
Full Speed USB is only 12Mbits/second where Hi-Speed USB mode is capable of a much faster 480Mbits/second.
Of course, this is device-specific...