This week's book giveaway is in the General Computing forum. We're giving away four copies of Arduino in Action and have Martin Evans, Joshua Noble, and Jordan Hochenbaum on-line! See this thread for details.
As much as it does any other technology. Whether or not you should use HTML5 and CSS3 for the interface depends on how you want to distribute your app, what your target audience is and (if you use the web) what browsers they're using. I don't think whatever happens to be at the back end is a major factor in your decision.