iPhone: Change the auto-lock delay
Contributed by qmchenry 
June 29, 2007 
Tagged: Apple iPhone
The auto-lock feature of the iPhone causes it to “lock” the touchscreen and turn off the display after so long since your last interaction. The default delay is one minute which may be too short for you (especially if you are writing Tech-Recipes about the iPhone!). If you would like to change the auto-lock delay (or turn off auto-lock completely), follow these steps.
To change the auto-lock settings, tap the Settings icon in the home screen. Look for the General button in the main Settings screen and tap it.
In the General settings screen, tap on the Auto-Lock option which will cause a list of options to slide in. At release time, there are options for 1, 2, 3, 4, 5 minutes and Never.
If you choose never, you’ll need to press the sleep/wake button (the thin black button on the very top of the iPhone and to the right as you’re looking at it) to make your phone go to sleep.
Even with the auto-lock feature on, you can still press this button to lock your iPhone.