Previously I mentioned a tool, PhyloPainter, which uses the HTML 5 <canvas> element to draw a phylogenetic graph. Here's what it looks like on my iPhone:
Not only are the arrowheads missing (as they are on Safari on all platforms, not just the iPhone), but the labels have bizarrely been placed outside the canvas, flipped upside-down! The tool works fine on Firefox and Chrome. (Internet Explorer has not implemented <canvas> yet, and I haven't played enough with the interim solution, ExplorerCanvas, to get it working.)
I think the <canvas> element is a cool idea, and I'll continue to play with it. But it has a long way to go to compete with a cross-platform tool like Flash. HTML 5 may be "open"—but it also needs to "work".