Twinkler, a new application available for jailbroken iPhones allows users to locate friends on Twitter.

Got a jailbroken iPhone? Then you've got to download a fantastic app called Twinkle that's doing some amazing things to make Twitter even more useful for people while they're out and about. Besides being a delightfully simple Twitter client (see also: ThinCloud and Hahlo), Twilight's killer app is its location tool, which taps into the LocateMe feature introduced in iPhone firmware version 1.1.3. Using this, it can narrow down not only where you are (to be included in your Tweets), but it also lets you see who's around you anywhere from 1 to 252,000 kilometers away using local mobile phone towers or your Wi-Fi connection.

You might be wondering how this would be useful for anyone besides potential stalkers. The answer is that if you're in a Twitter-rich city, drilling down to 1- to 5-mile radius around you will let you know all sorts of things going on in your area as they're happening.

Twinkle's other fantastic feature, which I demo in the video below, is the built-in photo integration that uses the iPhone's camera to take pictures you can attach to your Tweets. The only catch is that you've got to be using Twinkle to see the photos. It's fantastically simple, and something I think will make its way into Twitter applications for other handsets.

I fully expect it to be released as a standalone application in the iPhone App Store in a few months when Apple updates the firmware.