If you were wondering if HTML5 has what it takes to be a real contender in the mobile space, check out Google's latest offering: 20thingsilearned.com. The URL features a story book entitled "20 Things I Learned About Browsers And The Web". While the content itself is entertaining and educational, done in a storybook style, and featuring information about browsers, browser extensions, plug-ins, and more, it's entirely built in HTML5 and features some pretty incredible web effects. For example, you can view a table of contents, turn pages with a curl, similar to the iBook platform, and even exit the page and resume where you were reading from.
The 20thingsilearned demonstration definitely shows what's possible in HTML5, and continues to blur the line between client-based apps and web-based apps. I haven't tried it out on my iPad or Samsung Tab yet, but I will be doing that shortly.
Before stumbling on Google's latest offering, I had really only seen some experimental games using HTML5, including Google's own PacMan. Google's latest offering has definitely gone far beyond that.