The 500MHz processor in the original Pre really does hold back WebOS. Running an overclocked custom kernel, I have mine set at 1GHz, makes a huge difference to the usability and surprisingly doesn't reduce battery life by much (which is partly due to the custom kernels clocking the CPU back to 500MHz when the screen is off).
It looks like HP/Palm have learned from this and aren't going to make the same mistake twice, the more recent videos of the Touchpad show how much they've optimised the UI to remove the lag:
http://www.precentral.net/webos-3-0-optimizations-make-smoot...
As I was completely unaware of overclocking in WebOS and specifically for the original Pre (which I have), I'll save the user the bit of googling I did to find overclocking. I had no idea it was this easy in preware:
It looks like HP/Palm have learned from this and aren't going to make the same mistake twice, the more recent videos of the Touchpad show how much they've optimised the UI to remove the lag: http://www.precentral.net/webos-3-0-optimizations-make-smoot...