It slightly concerns me that "the community" is going to have a direct say in UT4's development. First, many developers and pundits have said that whenever a community starts to dictate the course of a game, things often go south, since the most vocal members of a community very often don't represent the majority of the playerbase. (I believe TotalBiscuit has pointed to WoW as a great example of this, though I haven't played it myself.) Secondly, I love UT and I've been playing it from the start, but I'm not a hardcore arena shooter player. Advanced techniques like bunny-hopping, strafe-running, and all the crazy stunts described in this thread simply don't interest me. As far as I'm concerned, many of them are glorified bugs and should either be removed entirely, or alternatively made more accessible for new players through tutorials and/or better in-game feedback. (See: skiing in the new Tribes, rocket jumping in TF2, combos in fighting games.) But I reckon that most of the people interested in the project at this early stage are exactly those kinds of advanced players. As a result, I fear that we'll get a game that's too obtuse for the "filthy casuals" (such as myself) who will be required to keep it active in the long run. Contrary to the current zeitgeist, I don't believe it's enough to balance a game around the competitive community in order to make it fun for everyone. Competitive gamers are a niche; people like me, who play for fun with a few friends over a couple of beers, are the mass market.
With that said, I'm really happy to see that there's going to be a UT4, and I'm looking forward to following the development. It's been a while since the last great arena shooter, and I hope we'll be seeing a resurgence sometime soon!