Venji on 28 April 2011
After doing some reseach I found a nice little site : http://www.thinkingwithportals.com/
People are already doing some early custom maps without the SDK (which won't be out for a couple of months) haven't tried them out yet but there is about 4 single player maps out and a 10 level co-op (including a hub). PC only and you have to access the ingame console as the menu doesn't yet support them. The maps come with a Readme.txt to explain how to do it.
(Going to try them out tomorrow - love the royal wedding 
)
Playing : PC AOE, DiRT 2, Runes of Magic, Wings of Prey & Planetside 2
Wii U : Nintendoland, Super Mario U & Fifa 2013 demo
DS : Guitar Hero : On Tour
Formerly unknown as Vengi
