This is a triumph.

Valve showed more Portal 2 co-op gameplay at the 2010 Penny Arcade Expo last weekend.  They say the co-op mode will be double the length of Portal 1 and link players via internet, local connection, or on the same TV/monitor using split-screen.

Four excerpts are below, demonstrating the ping tool (shows your partner where to aim a portal instead of saying “over there, no, there”), the return of the infinite jump, the new “hard light bridge”, and some of the gestures, like pressing a button to make the players hug.  All games need a “hug” button.  Right next to the “rip out somebody’s intestines and fashion violin strings for the tiny violin you’ll play for them” button.

Here’s the ping tool in action:


Hugging:


Hard light bridge:


Infinite jump:


Videos via Kotaku.  The full-length HQ video from the PAX 2010 conference is available at GameTrailers.