Interestingly, the Facebook client for Android has just moved back to being a native app after months of poor performance from the HTML5 implementation.
Heh. Yeah. Although I'm sure their programmers missed a few critical (yet obscure) things to enable HTML5 to perform well on low-end hardware, I'd personally stay away from any W3C standards for any project I do. So um, it's still okay as long as you're extremely conservative and know which corners to turn, but I find a lot of *professional* HTML5 programmers fail to grasp the quality of such an implementation. This hassle is still not worth my time; I don't like web applications anyway.