http://www.gamasutra.com/view/feature/131503/1500_archers_on...
http://twvideo01.ubm-us.net/o1/vault/GD_Mag_Archives/GDM_Sep...
It is the lock-step model but with state rewind, so that you get near zero apparent latency from your own actions (at the cost of animations from other player actions starting a few frames in). You occasionally see things like a successful hit from you on an opponent be rewound and applied to a block from him/her instead.
For co-op games where aren't you aren't closely interacting (like in riding along in a vehicle) it can be a near conflict free and zero latency experience.
You can use various levels of it, accepting a reducing a 100ms ping into a 50ms delay will get less conflicts than reducing it all the way to 0.
https://developer.valvesoftware.com/wiki/Source_Multiplayer_...
http://gafferongames.com/networked-physics/introduction-to-n...
http://gafferongames.com/building-a-game-network-protocol/
Not game specific but will get you into the mindset of how a networked game functions.