A previous Reddit post gave some indication:
It's basically Lightning-network style payment channels but for arbitrary state updates. Participants in the Dapp send messages with transactions to each other that update the state but do not publish them to the chain. If one of the participants leaves or tries to cheat the other one can at any time publish the latest transaction to the blockchain to finalize the state. Just the threat of publishing to the chain is enough to keep participants honest.
Are there any architectural diagrams or web3js code examples for implementing State Channels?