Google announced the other day that it will buy Jambool, the payments platform for social networks — on nearly the same day that PayPal CEO Scott Thompson revealed plans to create a micropayments product. Google’s move was better.

It is fair to say that online payments is officially the hottest startup sector in Silicon Valley today. With such massive potential, the gold at the end of the virtual rainbow is not necessarily the social graph, but how the social graph pays for stuff. And Jambool is right at the heart of it with its Social Gold platform. Social Gold allows anyone who knows how to install an API (that would be nearly everyone who knows the difference between PHP and PCI) to charge for stuff on social networks, including Facebook, MySpace, Hi5 and Bebo. That is a powerful tool, indeed. Think about it. Anyone with a Facebook page can now monetize, well, anything. And there are a lot of people with Facebook pages.

This is effectively the game PayPal wants to get into — only it is late to the party. Thompson said PayPal would introduce a micropayments product by yearend, even as Jambool now gets a Google turbo charge.

Yet, if players of Zynga’s FarmVille, for example, want to buy something in the game with PayPal, today they have to exit the game to consummate the transaction. Not exactly an ideal situation for game players.

Sure, PayPal has scale and even today does far more virtual currency transactions than Jambool, but Jambool now has Google behind it. I expect Jambool to become the default virtual currency platform for Google — and that gives Jambool a massive leg up immediately. Advantage: Google.