So it seems that you can actually get to the applications on iTunes already. There's no link (that I've seen) to the App store, however, do a quick search for AIM, which we already know is a confirmed app. You'll then see the AIM app, and after it is downloaded, you can click the "Get More Applications" button at the bottom right corner of the Applications section.

There are a ton of Applications already up for download, 552 to be exact. 135 of those apps are free to download. I'm pretty sure that the next hour of my time will be dedicated to sifting through pages of new stuff for the iPhone 3G that I don't even own yet.