Navigation
Standard websites have evolved toward placing navigation along the top and sides. For mobile optimized websites, this just doesn't work. Mobile screens are so small that top navigation could easily cover much of the screen and force users to scroll before seeing the first elements of your site's content. It's counterintuitive, but in most situations mobile websites play better with navigation at the bottom of the page. This way, users see the vital content they want with the very first screen full of information. And because they are used to the idea of scrolling down to see more, scrolling to find the mobile site's navigation makes more sense than it does on a standard website. In many cases, that first screen can display a content menu with links to half-a-dozen sub-topics or categories of content that mobile users are likely to want.
Incidentally, users of the standard web are far more forgiving of "under construction" or "coming soon" signs than mobile users, who absolutely hate broken links. Even if you have plans to expand or modify your mobile website very soon, make sure everything you put up for mobile users actually works. Add any new or changed links into the site's navigation only after you flesh out their content.
It's also useful to include a "mobile site map" somewhere on your site. Having one from Google helps your ranking in Google's mobile directory, and it also helps Google keep up to date as you change your website's pages. With the link in place, Google will often register page changes in a couple of days rather than a couple of months. Similarly, Yahoo has a "yahoo mobile submit" page where you can register your site and help them track your mobile pages more closely.
