There is a lot of speculation that patch 3.1 will drop tomorrow. I'm not really buying into that speculation yet, but the background downloader was active over the weekend delivering up another part of the patch files. That is a strong indication that the patch is nearing, and at the least means guilds should start ramping up their preparation to push into Ulduar.
For many hard core raiding guilds this means making sure the right members will be on and fully buffed and ready for lots of raiding as soon as Ulduar opens up. Equally important is making sure that reserves and alternates are available so progression raids don't grind to a halt.