After seven months of indigestion, Chipotle Mexican Grill (NYSE:CMG) got it right. The burrito baron's new ordering tool for the iPhone and iPod Touch is a hit.

Of the 125 users to rate the app as of this writing, 97 give it five out of five stars. By contrast, Dunkin' Donuts' similar-yet-not-as-functional Dunkin' Run for the iPhone earns just two and a half stars on 281 ratings. Ouch.

The big difference between these two is that Dunkin' Run organizes your menu on a printout, but doesn't deliver your order via the iPhone. The new Chipotle ordering app does, and fixes a key complaint with the 1.0 version of the software by tapping into the iPhone's geolocation features to hook you up with the closest store before taking your order.

Users couldn't be more pleased. Here's a sampling of the comments about the app left at the iTunes Store:

"Great. App needs to be on every iPhone and iTouch everywhere!"

"I've been waiting for something like this and it's better than I imagined! If you love Chipotle but hate standing in line, you HAVE to have this app!"

Even better, some users are talking about features they'd like to see in the 3.0 version. One wrote to say he'd love for Chipotle to somehow integrate email so others could "enter orders into your bag on the go."

Expect Starbucks (NASDAQ:SBUX) and former Chipotle parent McDonald's (NYSE:MCD) to take notice. Both have significant drive-through businesses that could benefit from a well-designed mobile ordering app.

Apple (NASDAQ:AAPL), meanwhile, must be thrilled. Software like this is what sets the iPhone apart from its chief rivals: Research In Motion (NASDAQ:RIMM), Palm (NASDAQ:PALM), and every handset that runs Google's (NASDAQ:GOOG) Android OS. This software turns the iPhone into a platform for business, entertainment, and now food.

Which reminds me: It's lunchtime here. My iPhone's calling for a loaded carnitas burrito with guacamole. And so is my stomach.

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