While some people are upset at the lack of cross-realm support for raiding, others of us are relieved. This means no cross-realm raid stealing, no cross-realm ninjas, and no cross-realm toy trains for us to smash. It is also fairly difficult to get the same group of people back later to finish a raid when they're scattered across your battlegroup.
However, some of the new features include the fact that the Looking for Group channel will be turned on by default for all characters and will be available in major cities, just like Trade and General. It will also be uncoupled from the LFG and Raid Browser interfaces. This means that those people who currently spam Trade with raid requests can move over to LFG and still hit their intended audience.
Right now, it also looks like you can queue for both classic and BC era raids as well as the current level content from the interface while on a level 80 character. I'm not sure if this will stay in as a similar feature was available in the normal LFG tool, but was removed a build or two later. There are still a few rough edges, but it appears to be coming along nicely.
Patch 3.3 is the last major patch of Wrath of the Lich King. With the new Icecrown Citadel 5-man dungeons and 10/25-man raid arriving soon, patch 3.3 will deal the final blow to the Arthas. WoW.com's Guide to Patch 3.3 will keep you updated with all the latest patch news.