I think being mobile-optimized is one of the niftier features of our new blog service. Using a plugin (WPMS Mobile Edition), we are able to simply flip a switch and … pow! automagically enable mobile-friendly blogs.
Curious what this looks like? Here are a couple screenshots of the reDUX blog taken on my iPhone.
Shiny! If you are running your own WordPress site (just a single site, rather than a multi-site installation like ours), you might want to try something like WordPress Mobile Pack.