If you were looking for yet another reason to convince you to jailbreak your iPhone 3G or 3GS then you should certainly consider the option to take HDR photos on older devices which will be available with iOS 4.1 jailbreak.
The iOS jailbreaking community has consistently tried to offer features which Apple has stopped supporting in previous generation models. Multitasking was possible on iPhone 3GS even before Apple announced the iOS 4.0 and now you can add the ability to take HDR photos on your iPhone 3G and 3GS with a few string tweaks.
Once the jailbreak for iOS 4.1 is released for the public, you can follow these steps to enable HDR photos:
Make sure you have installed OpenSSH through Cydia. When it’s installed, SSH into your device (I recommend you also use the “passwd” command to change your password from the default “alpine”)
If you have an iPhone 3G, grab the file located at /System/Library/CoreServices/SpringBoard.app/N82AP.plist
If you have an iPhone 3GS, grab the file located at /System/Library/CoreServices/SpringBoard.app/N88AP.plist
Add a key named “hdr-image-capture” with a boolean value of “true” to the “capabilities” section of this property list
Save it, and use SSH to replace the copy on the device with your modified version
Restart SpringBoard, or just reboot your device. You should now have access to the HDR setting in the camera application.