Just a friendly reminder. If you are a MobileMe subscriber and have upgraded to the latest 3.0 iPhone OS, make sure to enable Find My iPhone on the device.

Here’s a real life scenario to understand just how useful the service could have been. This morning Syl and I carpooled into work. Four hours after dropping her off, I receive a call from a unknown number. It’s Syl calling from work and she has no idea where her phone is. Immediately, I think of Find My iPhone and log into MobileMe. Shock and horror: Find My iPhone is not enabled.

If the service had been enabled on the handset, I could have had a good idea whether a) Syl had simply forgotten the phone at home, or b) left home with the phone – which had accidently fallen out of her bag. It’s an interesting technology. Not entirely accurate, but a useful approximation of where the phone might be.

I’m kicking myself right now because the feature is disabled. I plugged her phone in, upgraded the handset to 3.0, enabled OTA contact syncing, but neglected to dig down a few more menus to enable Find My iPhone. I logged into at&t wireless to check call history and discovered last call activity was 8:50 PM (previous evening). I’m hoping the phone is simply at home somewhere. Assuming the phone is somewhere at home, I pushed a reminder to enable Find My iPhone. If it’s not at home, it’s probably a goner.

Need more proof on how useful the feature can be? Check out this story about pursuing the handset in real-time using MobileMe. Don’t have MobileMe yet? Purchase it through Amazon and kick a little something back my way.