Funnily, my quad Intel Core i7 (two cores both with hyperthreading) couldn't play the 720p Flash video on YouTube smoothly...

Impressive stuff! The thing I paid most attention to was the way they had figured out at least some way of what to do with those ARM cores. Getting four cores running at 75% (no idea whether they were throttled at the time) means there's some serious work being done. The usual mobile graphics benchmarks don't stress the cpu side as much the gpu side so Tegra3 wouldn't gain as much by running existing demos.