According to this, Infinity Ward's Robert Bowling reckons you're going to get exactly what you asked for in the upcoming pack of Call of Duty 4 downloadable content.
"It's a lot of community feedback, they want bigger maps, more buildings, more close quarters fighting," he said. "It's going to be really evident that it's stuff that they asked for. People in the community should have a good idea of what to expect."
There's no firm release date for the pack yet, other than "spring".