Ubuntu runs in a card, just like a WebOS program. While running Ubuntu you can therefore switch to other programs and it will continue in the background. Sort of like a VM.
Other places you can check out are WebOSInternals (their Wiki pages are often referred to as How-To-Guides) and WebOSRoundup.
And
www.xda-developers.com now has a WebOS and a Touchpad section, too. Though rather small and not nearly as thorough. In general they are best for Android and Windows Phone 7.
And now that MeeGo can soon run Android programs, WebOS shouldn't be far behind it -- that would mean all Android apps running just like WebOS apps. Much better than flashing Android!