Check Out New WotLK Features with WoW Talent Calculator
These talent trees should give you a good idea of what to expect from WotLK. However, the talents in the beta are more recently updated than those on the web, and of course neither one is written in stone until launch. Of course Blizzard has been known to tweak things after launch too if game balance is in question.
You can access talent calculators for each class, including the Deathknight, on the World of Warcraft website.