I was interested in something to measure speed and started searching. Quickly I realized that if I had a gps it made a lot of sense to be able to see VMG too. "Relatively cheap" was part of the specs too... So all that pointed to Iregatta app. I'm not ready to put my ipad on the cat yet, even if I had an appropriate hard case, but I might try with my daughter iphone 3gs (I'm working on that...). I made some tests walking and the ipad works great but the iphone 3gs doesn't. Walking speed seem to be too slow and I don't get speed reading. It seems that the iphone 4 and the ipad 2 have better gps than the iphone 3gs as I then read in google. So apparently I should be looking for an iphone 4 now.. But as it's not anymore on the cheap side, I'd like to hear opinions. Any body using it?