The Tech Report had a hands on experience with a NVIDIA Tegra based netbook at Computex. These systems aren't very powerful but will be available for around $199. Here's a snip about their experience:
Nvidia showed the netbooks playing back 720p video, streaming live Taiwanese TV, and running an alpha version of Firefox 3.6. Tegra handles video-related tasks quite well, and 720p trailers in particular looked surprisingly crisp and smooth. Nvidia tells us Tegra draws so little power that these netbooks should be able to play 720p video for 10 hours straight before exhausting the battery.
Web browsing was a somewhat different story. Although the slow Internet connection at the convention center didn't help, drawing page elements from a website like TR felt sluggish and caused the mouse cursor to go choppy occasionally. You can chalk that up to the Tegra SoC's 600MHz ARM processor core. Adobe Flash support was also incomplete, although YouTube videos actually played back reasonably smoothly—but Tegra's multimedia components take care of accelerating those.