I've been involved in a good number of projects recently involving location and tracking (a common term for the combination of these two is now positioning, not to be confused with positioning in a marketing sense or any other), and I continue to favor Wi-Fi as the preferred vehicle for in-building applications. My reasoning here is that Wi-Fi already has a rich capability and long history in positioning, and that Wi-Fi has a huge installed base and is now essential indoors everywhere simply for access. And good solutions for Wi-Fi-based positioning are available from many WLAN system vendors and a number of third-party suppliers alike.
The disadvantage to the Wi-Fi approach is that a reasonable density of APs is required to improve accuracy (spatial resolution). We generally assume we'll realize three to five meters square, but we've obtained one-meter accuracy with reasonable AP density. While more APs will thus be required in many installations towards this end, a labor-intensive and perhaps lengthy (read: costly) calibration process is also required for Wi-Fi-based positioning in most cases, depending upon the specific product involved. In many retail settings, though, adding more APs just isn't feasible - the APs have a cost (and more are likely not required here for access as capacity is probably sufficient for the current mission), their installation has a cost, more PoE switch ports have a cost, and logistics and management have a cost. So a lower-cost positioning alternative to more APs is clearly desirable.
And a good example of such is Motorola's new MPact Platform, which leverages a hybrid of Wi-Fi for coarse-grained positioning and Bluetooth Low Energy (BLE) beacons for the fine-grained part. Wi-Fi can be used to determine if a given client is present, both technologies can be used to identify an arbitrary zone, and the beacon used to determine position, at least with respect to a point on a circle whose radius is the distance from the beacon. So this solution may not be as accurate as the triangulation of densely-provisioned Wi-Fi, but it could be much less expensive if positioning alone is the goal. And, of course, all kinds of offers and services could be provided to consumers, making this approach very win/win/win (Motorola/retailer/customer). MPact also fits nicely with Motorola's efforts to close the gap between online and physical retail.
The key elements of MPact are a Motorola WiNG 5 Wi-Fi network, Motorola BLE tags, the client SDK, and server software, which includes analytics. Two further requirements are a dependency upon consumers having appropriate devices (equipped with both wireless technologies), and an appropriate app, most likely that of a given retailer. But given the popularity of smartphones, the continuing rapid turnover of the smartphone installed base, the consumer affinity for apps and the convenience they embody, and the low cost (US$5-15 each) and long battery life (2-4 years) of the beacons themselves, Motorola's hybrid approach could prove to be very popular indeed.
One additional challenge is that every Wi-Fi and positioning system vendor seems to take a proprietary approach to their own solutions; there are no standards here. This makes it difficult for application vendors to grow the industry, as numerous simultaneous implementations are often required. Motorola's solution is also proprietary - while it can work with third-party Wi-Fi infrastructure and beacons, the API and locationing engine are theirs alone. Eventually, app developers are going to demand a standard API (MPact could be a candidate here), and perhaps this functionality really needs to be embedded into the mobile OS for security and integrity purposes. Regardless, Motorola's offering is already impressive, with a number of partners signed up (see the MPact site or the press release) and other markets like hospitality beckoning.
By the way, Motorola Solutions' Enterprise business, as you may already know, is about to be acquired by Zebra Technologies. This includes the WLAN products and MPact, but we're not expecting any immediate changes to the product line. And this also means that a wireless LAN that can trace its roots back to the wireless group at Symbol Technologies, one of the true pioneers in wireless LANs, combines with Zebra's presence in barcode, point-of-sale, RFID, asset tracking, and printing to offer far more robust solutions - which, again, is what the era of sufficiency is really all about.