Above is the raid panel from the new LFG interface (click for full-sized image). Unfortunately, it isn't actually working at the moment and it isn't readily accessible in the PTR's interface. As you can see, the leader role isn't available at the top, so we currently presume there will be a special interface that the raid leader will get similar to the current "Looking for More" interface on the live realms.
The List button at the bottom isn't clickable at the moment, so we're not sure what pops up after it's been selected. Some of the raids are currently locked. This is a byproduct of the PTR as in previous test patches they had locked down those dungeons for testing prior to their release. From looking at the code, the new system should be able to tell if anyone is currently locked to a specific Raid ID and unable to join your new group. This should also be the case for any heroic dungeons that people run using the new LFG tool.
Unfortunately, we're still not sure if the Looking for Raid system will also be cross-realm. The developers have mentioned in the past that that they really don't want to have raids be under the same cross-realm system and I'd have to say that I agree. With twenty-five people possibly all from their own realms, the probability of having your raid's ID stolen goes up. There is also very little you can do to track down who did this or even talk to them about it later.
As this feature is incomplete, we'll be keeping an eye out for how it is shaping up during the PTR. It's a shame we won't be able to use it for the Icecrown Citadel testing on the PTR this week.
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.