I still consider keyword density as a litmus test for how I expect spiders to consider my pages. Even more important, but touching on the same concepts as keyword density, is the text-to-code ratio.
http://www.seochat.com/seo-tools/code-to-text-ratio/
And this is something I do spend time optimizing for. With all of the analytical scripts, forms, nestled navigation bars, etc, on a standard site, it's easy to become code-heavy and be penalized for it.
