Portal 2 co-op gameplay footage

Eight minutes of Valve's two-player PAX demonstration, and some screenshots

Valve has released a bunch of cinematically composed co-op screenshots fresh out of the PAX show underway this weekend.

Meanwhile, lucky attendees have had their cameras pointed at a co-op gameplay demo, in which Valve shows off the Ping tool - a waypoint market that enhances player communication - and several other clever co-op gameplay mechanics.

Valve also promises that the co-op and single-player campaigns will both each be longer than the first game's campaign was. And hearing that makes us very happy people.

When you're done with the below, check here to see more of the game's awesome new mechanics in action.