If you missed the original iKitt iPhone App review then you can read the full details here
http://shanemcdonald.org/myblog/2009-09-29/ikitt-ipod-app-review/

This is just an update regarding the iKitt iPhone App’s operation as a speedometer using GPS as you are travelling.

Turn the iPhone on its side and you get the classic Knight Rider / Kitt speedometer. As the iPhone gathers the GPS coordinates and positioning it calculates the actual speed you are doing (please do not do this when driving!! I don’t want people telling me they crashed when trying this out!).

A screenshot of the app in operation is shown below.

The speed of the iKitt speedometer is not realtime, sometimes it will update once a second sometimes longer. However it is quite accurate. The actual speed when testing above was approx 90kph.

I was very tempted to try this in a 737 when taking off from Gatwick recently but felt the “Please turn off all mobile devices” was enough to get me to turn it off.

Its a very good app and well worth the €0.79c price tag on the iTunes App Store, even if it is just for the retro sentimentality.