Functionality aside, one of the biggest differences between Microsoft’s Xbox LIVE gamer network, and Sony’s PlayStation Network (PSN) has been the cost: If you want to play against other gamers on Xbox LIVE, you need to pay around $50 annually for Gold service (though various retailers offer discount cards); multi-player on the PSN is free.

But in a statement to VG247, SCEA president and group CEO Kaz Hirai revealed that the company plans to launch a premium, pay-to-play service on the PSN: “We are studying the possibility of introducing a subscription model, offering premium content and services.” No details on pricing, what the premium content would include, or a launch ETA—but Hirai made sure to note that it wouldn’t be in lieu of the free service.

Sony (NYSE: SNE) is already making money through PSN Store game downloads and add-ons; the company said October was its “highest month” in terms of revenue, with downloads up 60 percent year-over-year (via Gamasutra). But adding a subscription option would definitely move the company closer to its goal of getting the games business “profitable” by 2011 (via the AP).

Microsoft (NSDQ: MSFT) has kept mum on how much money it makes from Xbox LIVE Gold subscriptions, but leaked documents (revealed by our own Joe Tartakoff, when he wrote for the Seattle P-I) showed that subscription revenues from Feb 2008 to June 2008 were at least $280 million.

• Leaked Documents Shed Light On Microsoft’s Xbox Live’s Revenues