I imagine a user produced content site awarding a virtual currency, we'll call it bitgold, to users who made popular content, or perhaps promoted content early on which became popular. The website earns revenue, buys gold and puts it in a treasury. Then users can trade in their bitgold for real gold. The site can manipulate/maintain the exchange rate by issuing more bitgold. I imagine that this is the way the government will function in a few years, when the Internet encapsulates the government.
If google buys digg, between digg, youtube, and blogger, they would have everything they need to start such a system. Perhaps we'll see a single service emerge from all three.