To add to this, I emailed Valve twice about Chasm and never got any response, guess they didn't like it. I think it is slightly odd that they have gone virtually completely silent on community maps. The last one to be released was koth_king, but that was developed with Valve and not in public. So the last grassroots release was Gullywash which is more than a year ago now. I haven't had the time to work on maps because of university work and so I kind of only come here intermittently now, but it does feel as though there has been a kind of downturn in custom mapping fortunes ever since MvM was released.
I do think Valve are still interested in community maps, they even provided an example map in the SDK for MvM when it came out, but I don't think there have been any custom MvM maps of note. Obviously though there's the new contest, so that should change in future. Special Delivery was pretty much a disaster of a game mode, nobody's really touched that since it came out.
I am really flabbergasted as to why they haven't opened a map workshop yet, it would really help reinvigorate the mapping community, especially if Valve provided some kind of financial incentives in-line with what item creaters make. Though other people have said here that they are working on that, stamps haven't really worked as planned, so it's kind of a sticky situation. They could certainly do a paid-by-played scheme for MvM maps, given the tour of duty system, but for other game modes? I don't think it really works out.
I think your best hope of getting a map in the game at this point is to make a MvM map, since it seems to be where Valve is focusing their attention at the moment. I don't personally think that MvM is as shit hot as it's made out to be, you don't form communities on 6-player MvM servers, that's for certain, but it's the newest thing in TF2 right now.
Added new checkout dialogs and taunt-activated effect to raise awareness for Community Map Stamps
Anyone know what this is? Was in the most recent update. Seems like they added some strange parts for each map as well.