What seems to be WebOS at first glance is actually TealOS, a downloadable WebOS-like skin for older Palm devices with PalmOS 5 (They offer a Trial version and a Full Version for $14.95 USD). The Software is loaded with parallel features of the WebOS including, live saved cards (multiple applications opened at once), and even the popup wave launcher. In other words, it'll will transform your clunky palm device(s) to a spanking new Pre, not really...
From what I've heard, the TealOS is a bit sluggish and has quite a few bugs that needs fixing. If you're gonna download the Skin to your Palm device and pretend you're playing with the pre, we'd love to have your feedback on it!
This explains everything for this post by engadget.
Update: An updated version of the skin is released (Version 1.03) and its much more stable now. engadget linked to us! :D