If you set aside the five or so hours it took to download Apple's iOS 5 this weekend, you were richly rewarded with a suite of new functions for your favorite brain-cancer-hastening communications device. And none were niftier than "Find My Friends" — appointed in the finest iNaugahyde, it's an app that allows you to plot your friends on a map as if they were enemy ships on a blinking radar screen.

Here's an example of how you might use it:

Friend 1: "Where's Bob? My birthday dinner started 45 minutes ago!"
Friend 2: "He just called. He said he's in a cab on the way here."
Friend 1: "Really? Because according to Find My Friends, he's still in bed."

Voila! Friends found. (Fights, resentments, and passive-aggressive paybacks to follow.) If it sounds invasive, you can take some comfort in the fact that you, and only you, must accept a Find My Friends invitation before it can begin tracking your whereabouts.

But what if someone had accepted it on your behalf without your knowledge?

That was the scenario described by a Manhattanite in the MacRumors forum, who enabled the feature in a new iPhone 4s he had bought for his wife, whom he suspected was cheating. He wrote:

I got my wife a new 4s and loaded up find my friends without her knowing. She told me she was at her friends house in the east village. I've had suspicions about her meeting this guy who lives uptown. Lo and behold, Find my Friends has her right there.

I just texted her asking where she was and the dumb b!otch said she was on 10th Street!! Thank you Apple, thank you App Store, thank you all. These beautiful treasure trove of screen shots going to play well when I meet her a$$ at the lawyer's office in a few weeks.

Asked by others to provide some visual evidence of the exchange, he posted the screenshots you see above, adding:

she said she is in meat packing district which is on 12th street. I DONT THINK SO. Appreicate the support. not my finest hour here but going to get better soon.

A man, just minutes after learning that his wife was cheating on him, rushes to an Apple forum to show off his "beautiful trove" of incriminating "screenshots." A fishy scenario? Sure. It might easily be fake. On the other hand, it might not. So how can you avoid a similar fate? Beware jealous boyfriends and spouses bearing GPS-enabled gifts. Leave Find My Friends off your app list. And, probably the best policy of all, don't cheat. It could come back to bite you in the a$$.

[MacRumors Forum via Edible Apple]