I have the console version so I'm completely at Valve's whim as to when or even if I can get some new maps. Hell, I'd even pay for the 3 other maps from the first game if they'd let me. I keep hearing rumors that they're going to be putting out more stuff , but it is from Valve so who the hell knows when they're going to actually get around to releasing it.
 
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(Wikipedia)
An additional downloadable content package will be released sometime after the April 2011 release of Portal 2. Valve have detailed that it will include a community-created campaign called Cold Stream created by Matthew Lourdelet, and support for three of the original Left 4 Dead campaigns in the same manner as No Mercy above along with Crash Course (DLC campaign for the original) which was confirmed in a blog.
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Cold stream is in beta I think. I played it a wile ago. 

I would also check out some community maps. There are some good ones.

@Alex_Murphy said:

I have the console version so I'm completely at Valve's whim as to when or even if I can get some new maps.

Unfortunately for you that's the problem right there. The PC crowd have had those maps for ages plus fan made custom maps. I would suggest that if you have a capable PC then ditch the console version.

Nah

Therein lies the problem with Xbox versions of Valve games. PC users have been playing these maps for awhile as Valve has worked on them and pushed them out over time, but because of the way Xbox Live works they can't do the same on consoles until everything is done and they can package it all together.

I would suggest that if you have a capable PC then ditch the console version.

Any update on this from all you L4D2 PC players? Is the beta over yet? I really am itching for a reason to go back to that game, but I get the impression this DLC is never going to see the light of day on the 360.

I know your answer will be "Play the PC version", but all my friends own the Xbox version... so I'd rather be able to play it with them.

@Alex_Murphy: This would be awesome: I really hope they do release it for 360. Like you, I can't afford a gaming PC and my 360 meets my gaming needs just fine. I wouldn't expect the console to get this fan made content right away or in its "raw" state, but I don't see why Valve can't release it now on Xbox Live as an additional DLC pack now, several months down the line, after it's been checked over and polished.