The best talent build for Marksmanship Hunters has been 7/57/7.
I'm sure other builds exist but this is the most frequently and best performing one that I've seen if DPS is any indicator of success.
There are 57 points in Marksmanship that you will have available to you, the 7 in Beast Mastery and the 7 in Survival seem to be almost mandatory, you may have some flexibility in the marksmanship tree.
The Marksman Shot Rotation for Raiding is going to look like: Kill Shot > Aimed Shot > Chimera Shot > Serpent Sting > Arcane Shot > Steady Shot as discussed in the paragraph below.
Please don't take the shot rotation literally and use common sense.
You're going to want to have Serpent Sting applied before you use Chimera Shot.
The reason it appears to the right of Chimera shot is after the first application, you won't ever really have to use it again until you switch mobs because Chimera Shot refreshes the timer, so I gave it position 4, easy enough to reach with one hand but not up there in the first 3 shots.
You're going to actually end up pressing 4, 2, and then 3 to start a fight and then spam whatever comes available (besides serpent sting) from left to right.
All 6 of my shots are macros that all contain the text listed below in each one (swap the correct tooltip/cast for the proper skill): #showtooltip Chimera Shot /cast Rapid Fire /cast Kill Command /use 13 /use 14 /cast Chimera Shot This allows me to not have to worry about any cooldowns ever.
Rapid Fire, both my trinkets, and whatever else you might have can go into these macros.
Marksmanship Glyphs Major: Serpent Sting, Hawk, Kill Shot It is essential that you have the proper glyphs, talents, and rotations prior to entering the Icecrown Citadel 10/25 mans, as they are somewhat challenging (until everyone gets gear that is)