Glameloft recently demonstrated their multiplayer games for the N-Gage at a trade show recently. One of the games, Tom Clancy's Splinter Cell/Team Stealth Action is exlusively for the N-Gage, and features a new cooperative mode, allowing puzzle solving and new situations that can only be resolved through cooperation.
Gameloft say the Team Stealth game will be played over Bluetooth, but has made no comment about whether it will be available to play over GPRS.