I have heard hundreds of people on the Net complaining about the browser for the DSi. Complaining that it does not support Flash. I have even seen numerous petitions trying to get Nintendo's attention. Because the DSi doesn't support Flash, this means that you won't be able to play videos, or most games on the DSi's browser. The DSi supports HTML5. Most people think this sucks, as HTML5 can't play videos, or a bunch of other things. And because of the limited memory on the DS, if you load a page with loads of images on it, it often won't load completely. But I think HTML5 could mean great things, a blessing in disguise, a sheep in wolves clothing. HTML5 can open up a whole new range of oppertunities. I would like to know the capabilities of HTML5, and what you can do with it.
The DSiPaint app uses the HTML5 canvas for drawing on the screen. Also, check out some of the DSOperaSDK demos with the 3D shapes and raycasting. Those are all HTML5 canvas.