One of my favourite iPhone apps stopped working last week. It uses the built-in GPS to track where you have been and can also place photos on a map that can be viewed on-line after uploading.
Unfortunately the new iPhone software update caused EveryTrail to crash. This problem has now been fixed and the new version takes advantage of the iOS 4's new 'multiple-tasking' facility.
So EveryTrail will continue to track without you having to remember to switch it back on after taking a 'phonecall or using another app.
It will be interesting to discover how long it will track on a full battery.
EveryTrail is also available for other mobile platforms.
The basic app is free but I haven't seen the need to pay for the other options.