Massively outlines a new system implemented in EVE Online to reduce the impact of gold-farming (or ISK farming in this case) in the sci-fi MMORPG. The new system involves something called a Pilot License Extension (PLEX), which will join the banhammer in the battle against real-money transactions. They outline this in detail, and here's a portion:

The other half of the CCP Games offensive against RMT is the 30 Day Pilot License Extension, typically referred to as "PLEX."

A PLEX is essentially an in-game item that represents 30 days of game time. They can be traded or given to other players, bought and resold. Once an EVE Online player has a PLEX in his or her possession, all they need to do is right click and credit those 30 days to their account.

The principle behind this is what's already been established by some of the free-to-play games on the market. Those with disposable cash in real life but who are short on time can buy game time codes and convert them into PLEX, so they have ISK to spend in-game. (One game time code = two PLEX.) When they sell PLEX on the market in EVE, that's money that players injected into the game that didn't go into the wallets of aklfjalkfjd and his merry band of ISK farmers.

Likewise, players who have more time to rack up the ISK through gameplay can buy PLEX in-game on the market, and play for another month without having to pay a subscription fee.