Very early, but there is a very strong consenus on the Colts pick.
Here is the breakdown of the pick from the 25 latest drafts from the Hail Redskins Mock Draft Database.
Colts Pick in 7 mocks" DT-Peria Jerry (Mississippi)
4 mocks (each): DT Terrence Cody (Alabama)*, DT- Sen'Derrek Marks (Auburn)
2 mocks (each): DTs- Evander "Ziggy" Hood (Missouri), B.J Raji (Boston College)
1 mock (each): DT-Al Woods (LSU), LB-Brian Cushing (USC), LB-James Laurinaitis (OSU), WR-Darrius Heyward-Bey (Maryland), OL-Max Unger (Oregon), DE-Everette Brown (FSU)*
That's 20 of 25 picks at DT, with Peria Jerry the most popular.
*=I try to be nice about peoples mock drafts since it's a not an easy thing to know every teams needs and scheme and I appreicate people trying. These two picks (Cody and Brown) give a good example of people who are trying, but just don't know enough and people who have no clue. The Colts need a big run stopping type DT, Cody is that, but he's waaaaaay to far to that end of the spectrum. Cody is 365lbs, he's a nose tackle, or a Grady Jackson type 4-3 DT. He's not going to move the way the Colts want from their DTs. I'm not going to fault someone for not knowing every teams scheme. Being completely clueless on a team's personell on the otherhand?
Everette Brown, DE, Florida St. The Colts do not have much of a defensive attack and opposite Dwight Freeney I just don’t see much there. That is why the Colts seem very interested into Everette Brown. Link
All the Colts have opposite Dwight Freeney is a 2008 Pro Bowl DE with 50 sacks over the last 5 seasons (which is actually a few more than Freeney has in that span).
So back on topic the early consensus is a DT with Peria Jerry the leading candidate.