HTML5 Audio Safari extension currently replaces the default Tumblr audio player (with or without Flash) and WordPress Audio Player (without Flash).
Comes in very handy when combined with John Gruber’s suggestions for running your Mac Flash-free.
(Also, and somewhat unrelated: I’ve finally gotten tired of the many errors the Delicious-to-weblog plugin was throwing, so I’m going to experiment with moving away from using Delicious as a link aggregator, and just post when I find something interesting. Old-school blogging. Imagine that!)