The issue seems to have started on December 16th, with a change in the way Apple serves AppStore content to the devices. Luckily (and before we could even post about it), Apple seems to have addressed the issue, as confirmed by Engadget.
Users on the thread are still getting mixed results, but hopefully all will be back to normal shortly.
Whenever I go into a specific app in the app store, none of the buttons work properly.
1) clicking on the price no longer downloads the app,
2) the ratings button does nothing,
3) the ‘tell a friend’ and ‘git this app’ buttons jump back to the top of the app window,
4) pictures usually don’t show up. They usually appear as five gray rectangular boxes with white borders (though in one app one too-large-for-the-window picture shows up (see pic),
5) the ‘app support’ button still goes to the developer’s website.
6) the ‘top in-app purchases’ banner is just text now.
In case you’re wondering about the outcry of iOS 3 users, theres quite a few out there, since the original iPone and first-gen iPod Touch don’t support iOS 4. And even users on newer hardware have chosen not to upgrade to iOS 4. In the meanwhile, if you’re still being affected by this issue, you can still download apps from iTunes on your computer and sync them over.