A new Build 9637 was already deployed yesterday and contains several class changes, emblem of conquest (Ulduar 25) items, and some other things.
You can refer to World of Raids or MMO Champion for a detailed list of changes.
The complete Ulduar ingame maps have also been added, you can look at them here.
Blizzard also announced the next PTR Ulduar test schedule:
On the North American test realms:
- Flame Leviathan (Normal, i.e. 10 Player Mode ONLY) - Tuesday Night, March 3 at 4PM PST (or after the PTR servers come back up) through tomorrow.
- Ignis the Furnace Master - Wednesday night, March 4, starting at 7pm EST/4pm PST.
- Hodir - Thursday night, March 5, starting at 7pm EST/4pm PST
- Flame Leviathan (Normal, i.e. 10 Player Mode ONLY) - Wednesday Morning, March 4 at 01:00 CET (or after the PTR servers come back up) through tomorrow.
- Thorim - Thursday night, March 5, starting at 7pm CET.
- Freya - Friday Night, March 6, starting at 7pm CET.
You'll find the description of all the siege engines that players will be able to use during the encounter.
Even though it could be fun, I'm strongly doubtful about siege engines in raids. They have already proved very bad in Wintergrasp when lag is so bad that the only thing you can do is aoeing, something at which they excel. I wonder if characters will have any sort of influence in this fight, siege engines can't be healed, and you can't use any ability when you're into them ...