After a bit of research I can answer my own question. The full way to get flash using the an nvidia ion gpu on ubuntu 10.10:
Install the new flash 10.2 beta:
tar zxvf flashplayer10_2_p2_32bit_linux_111710.tar.gz
sudo cp libflashplayer.so /usr/lib/flashplugin-installer/
You may need to also replace flash in other locations if you have installed in multiple places (try using 'locate libflashplayer.so' for a complete list)
Then for gpu support you also need (this was the bit I was missing):
sudo apt-get install libvdpau1
If you also want it working in chrome try:
To verify it is working go to a high-def you-tube video and play it. While it is playing right click and select - video info. You should see "Accelerated Video Rendering" if it has worked.
These instructions worked on my acer revo with a nvidia ion gpu.
Also on my blog with more links: http://decodify.blogspot.com/2010/12/getting-flash-102-beta-gpu-acceleration.html