140 expertise rating for a shaman with 3/3 UR. even less if you're an orc using axes/fists.
"Expertise Rating converts into Expertise skill at a rate of 8.1975 expertise rating:1 Expertise at level 80, and reduces the chance for your target to dodge and parry by 0.25% per point of Expertise. 214 Expertise Rating is required to achieve 6.50% dodge reduction, which is the maximum observed value of any NPC. In 3.1 unleashed rage was changed to provide 9 expertise for 3 talent points. If you have specced for 3/3 Unleashed Rage you will only require 140 expertise rating to reach the dodge cap. Orcs also gain 5 expertise when wielding Axes or Fist Weapons (added in 3.2) so make sure to take that into account when determining your personal expertise cap." (EJ)
my, oh my what a simple google search brings up =]
edit: arggh ya beat me orc!! glad you found the info tho, next time google it like i did XD "expertise cap for a shaman", it was the first or second thing that came up heh