The Xbox Live status page (and our own abortive efforts to download stuff) reveals that the Xbox Live Marketplace is currently experiencing an interruption in service.
According to the site, "users may experience difficulties" browsing Xbox Live Indie Games, the Games Marketplace, or the Games for Windows Live Marketplace from either an Xbox or a PC. It's more than "difficult" -- in our case, at least, the XBLIG page returns no results at all.
Given recent history, it's tempting to jump immediately to topic of hacking. However, there's no evidence of that, so we're going to assume the blame lies with molemen instead. Molemen are stealing our Marketplace access.