We've come full circle on the iPhone software merry-go-round-- the first app we saw for the iPhone was a mockup built with Digg's API, and now Digg has released their own iPhone application.
And it works pretty well, even if you're not using an iPhone. You can log in right there in the interface, and even browse topics through a drop-down menu. Perhaps the biggest new feature is a "mini-permalink" page that will automatically grab the top 5 moderated comments from the regular Digg page and only show those. That right there is almost enough to make me browse the iPhone Digg rather than the regular Digg, even on my desktop-- the fewer and more useful Digg comments I can see, the better.
Kevin Rose also promises a way to see the top stories in the iPhone interface is coming, and since there is no way to actually add comments yet (you have to go to the main Digg page for the article to do so), they may work on that in the future as well. After all this app was supposedly thrown together in 48 hours-- Rose promised coder Joe Stump that if he did it in two days, he'd get an iPhone, and apparently he did.