Our intrepid YouTube adventurer Dan O'Halloran found this video posted back on the 5th of January this year detailing the Ulduar raid zone thus far. It was made using private server technology, and contains heavy spoilers. You've been warned.
When you watch the video you'll notice that much of it is incomplete. Large areas are nothing more than gray swaths with no content in them. This is intentional and normal – the areas just are not developed yet.
However there are areas which are vibrant and high quality. Parts of the place resemble (as expected) the ancient gods look to it. The place could (and will) be sitting right next to the Halls of Lightning.
Take a watch through the video when you have a moment today. And don't forget to check out the previews of the Tier 8 gear MMO-Champion is offering.
Update 7:38 p.m. EST: Looks like Blizzard had YouTube take the video down.