Andy Coggan has some articles about the pursuit on his blog. Especially
part 3 is about pacing (which is supposed not to be completely even). Your app could compare the actual split time with the planned split time and also indicate whether the rider has to go faster to reach a certain time. Ipad seems to be more useful for something like that. Jens got the pacing signaled on a tablet during the hour attempt.
(Nevertheless I'm not going to buy an Apple ios toy)