(Don't follow these links if you don't want spoilers)
One of our druids, Vykromond, decided what he really wanted to do last night was to go through pages of uncategorized spells and see if he can pick out which ones are associated with which bosses, thus painting a portion of a picture of the new encounters
(this isn't just a series of random links in the posts -- it has the ability descriptions pasted right in so you don't have to click through just to read them.)
Here they are:
<a href="http://www.stratfu.com/blog/2009/02/...freya/">Ulduar Boss Sneak Peek: Freya</a>
<a href="http://www.stratfu.com/blog/2009/02/...athan/">Ulduar Boss Sneak Peek: Flame Leviathan</a> (the vehicle boss)
<a href="http://www.stratfu.com/blog/2009/02/...hodir/">Ulduar Boss Sneak Peek: Thorim and Hodir</a>
<a href="http://www.stratfu.com/blog/2009/02/...uncil/">Ulduar Boss Sneak Peek: The Iron Council and Mirmir</a>
<a href="http://www.stratfu.com/blog/2009/02/...saron/">Ulduar Boss Sneak Peek: Yogg-Saron</a>
<a href="http://www.stratfu.com/blog/2009/02/...ities/">Ulduar Boss Sneak Peek: Random fun abilities!</a>
Remember: this is unconfirmed, data-mined data. It's (a) possible spoilers, and (b) possibly incorrect.
But the encounter looks pretty fun if even half of this is correct.