Looking at current depth charts and looking ahead to 2008.
I found depth charts for most of UGA's 2008 opponents (could not find one for Georgia Southern or Central Michigan). I counted the number of seniors listed 2 deep on offense and defense; I did not count special teams. Obviously some of these folks might leave early or even transfer or not make grades, so take it for what it is. It also does not take into account a person getting beaten out or big changes due to a change in offensive scheme which could happen at Central Michigan, Tennessee, Auburn and Tech since CMU might get a new HC, UT and AU have (or will have new OC) and Tech will have a new staff.
Team Off SRs Def SRs
USC 6 8
ASU 7 5
Bama 3 6
UT 4 6
Vandy 6 5
LSU 7 7
UF 3 3
UK 7 4
AU 6 5
Tech 6 10
For reference UGA loses 3 from the offense and defense
Not all senior losses are equal for instance UK losing Woodsen is a big loss compared to losing a backup FB on some other team.
There are also situations where the drop off is not all that great.
I do not see any UGA players going early to the NFL unless that are some that are in trouble academically that no one knows about.
What was amazing was looking at the SEC teams on UGA's schedule and seeing all the FR and SO listed as 1 or 2 on depth charts.