According to the job listings posted by Rockstar North, they are looking for experienced network programmers. When Grand Theft Auto: Liberty City Stories said it would have multiplayer, many hoped that it would let players shoot at each other (deathmatch). Sadly that did not happen, but their recent job postings show that there could be more complex online play in the future.
The minimal listing says that the Scotland-based shop is “looking to expand their experienced and talented teams” with the addition of…network programmers.

What will Network Programmers most likely do?
Network programmers specialize in code that allows for multiplayer gaming via a LAN, wireless connection, or online.

About the ad
The ad in question has been up for more than a month, meaning that positions remain open. That’s a sign the company is hiring for more than a few slots–which could indicate a potentially large project is in the offing. Since the network programmer job is at Rockstar’s Edinburgh headquarters, not at the handheld-centric Rockstar Leeds, it means that the game in development is almost certainly for a console or PC. However, with Rockstar’s history of debuting games on consoles–specifically the PlayStation 2–it is most likely the former.

While speculation is already beginning that that the network programmers will be working on the next-generation console version of Grand Theft Auto, it must be stressed that nothing is official other than the listing.

Source: Rockstar North’s Official Website (Go to Menu then Job Listings)