From Andrew Bone again: "SEC rule of signing no more than 28, but bring in a max of 25. This rule must also meet no more than 85 overall on campus on scholarship."
I think that means you can sign 28, but three will have to be enrolled elsewhere (jc or military school or they don't make it grade wise). AU has quite a few who are counting towards 2009.
Also from AB:
"Auburn has several who will backcount to the class of 2009. They are in the homestretch for a great class with Marcus Lattimore expecting to announce for the Tigers February 2. They may lose a couple in the closing weeks as well to LSU (Trovon Reed) and to Ole Miss (Shon Coleman)."