Today inMarket is beginning a huge rollout of iBeacons to grocery stores including Safeway and Giant Eagle locations in Seattle, San Francisco and Cleveland. The rollout will place the Bluetooth LE beacons at the entry of over 200 stores in the coming weeks and more after that.

Those iBeacons will be used in a variety of ways by inMarket’s apps initially as a part of its Mobile To Mortar program, and then partners down the road. The primary goal is to reach shoppers who they know with absolute surety are walking in or right near a store in order to maximize the effectiveness of messaging.

The beacons are small round devices slightly larger than a quarter that contain a Bluetooth 4.0 Low Energy radio and a small circuit board supporting it. The devices send out short-range signals that can communicate with smartphones like Apple’s iPhone and some newer Android devices. Those signals are picked up and interpreted by apps like inMarket’s current App Store offerings and are used to trigger a variety of different behaviors.

Apple added support for iBeacons with its iOS 7 software release last year, but we’re just starting to see the fruits of that inclusion now. Apple rolled out its own iBeacon solution in many of its retail stores — rigging up iOS devices (and some dedicated iBeacon units) to communicate with its retail store app.

The advantage to iBeacons or other similar Bluetooth LE beacons lies in a couple of key things. First, it’s very low-power, allowing devices to sip energy as they wait to hear a signal from an active beacon. Second, they’re hyper-local, allowing the beacon’s installer to pinpoint to within a few feet the location of the smartphone user that they’re trying to reach.

With GPS and Wi-Fi location having been a mainstay of devices for a couple of years now, you’d think we’d have solved the problem of telling exactly where a smartphone user is when the information is needed for an app to work.

That’s not the case at all says inMarket CEO and co-founder Todd DiPaola. He says that inMarket has done case studies involving its partners like Coca-Cola, Procter & Gamble and others that show an immense difference in effectiveness between offerings that are made to consumers right in the store vs. at home or elsewhere. The time-of-purchase power is incredible.

That’s why pinpointing location is so important. “If the person is 200 feet from the store,” says DiPaola, a scientist that graduated with a background in Molecular and Cell Biology from Berkeley, “that’s a big difference.”

DiPaola has since tuned his science background to digital marketing, co-founding Vantage Media and then inMarket, both of which are bootstrapped with funding from inside.

He says that inMarket has used millions of shoppers to help it pinpoint the ‘center’ of a store. Those center points have helped it to correct data from other databases like Google Maps or other marketing tools, which placed the center of locations in a parking lot or elsewhere. This could trigger an alert when it is ineffective or annoying to a user that is simply ‘in the vicinity’.

With iBeacons at the entrance to these stores, the location is nailed down to a few feet. This increases surety and decreases misfires. And the nice thing about iBeacons is that they’re part of a mated system. The user has to have an app installed and be in the presence of an iBeacon. You’re not tracking or annoying customers who have not at least obliquely opted in with a supported app.

There are a lot of buzzwords involved in this store marketing stuff by necessity, because brands will use it in a variety of ways. But there are some very concrete and simple applications that will show up in inMarket’s apps as of today. If a shopper is using its List Bliss app (a shopping list), a notification could pop up on their phone when they walk in the door of a store, telling them that an item is on sale. Or the CheckPoints app could tell them which items will earn them the most rewards points. All of this will be opt-in.

Simply put: when you know exactly where a person is, especially if that is at a store entrance, you’re able to far more effectively offer them deals, coupons, promotions and reminders that will make them shop more.

For now, inMarket’s system will work with its own apps, but there are possibilities for expanding it out to brand partners for use in their apps or even independent developers in the future.

“Besides Apple themselves, we are the first to take this groundbreaking technology out of single-store betas and into consumers lives throughout the heartland of the US,” DiPaola says. As one of the first big-scale rollouts of iBeacons into real working stores, inMarket’s offering is one to watch as we see the payoff of this new micro-location trend.