If you are iPhone user you should know that Apple does not provide any add-on features in the native iPhone camera app such as rapid shot and time delay. You can add these features by purchasing an app known as PictureMe. PictureMe is an app that add these add-ons, with this app installed on your iPhone you can set the timer delay between 0 and 25 seconds. The rapid shot feature allows you to set the number of pictures to be taken (max 5 in a row).
The video below shows that how the app works:
This app is available at Cydia under BigBoss repository for $1.99. You will need to jailbreak in order to use this app. To jailbreak your iPhone via sn0wbreeze follow this guide and for Redsn0w follow the guide posted here.