Bernard Lagat is making his half-marathon debut in March at the NYC half:
Someone correct me if I'm wrong, but I'm pretty sure Lagat has never run anything over 5,000m on the track. He was an 11 time All American in XC.
I don't think he's run a road race over a mile before.
Plus, he's a low-mileage guy. However, he's the smoothest runner I've ever seen. This should be an interesting to combination to see if he just runs out or steam.