The Bluetooth Low Energy standards comes in two different flavours, 'Smart' and 'Smart Ready'
One of the obvious use of Bluetooth Low Energy is in Beacons. Here is an excellent presentation on Bluetooth 4.0:
Bluetooth 4.1 brings new capabilities in Bluetooth for it to become a challenger for Internet of Things (IoT). Here is an extract from an article in Network Computing:
With 4.1, the Bluetooth SIG is aiming to become a major player in the much-hyped Internet of Things (IOT) market. While 4.0 steps on Wi-Fi’s turf for location-based interaction with client devices, Bluetooth 4.1 looks to leverage Bluetooth's broad name recognition, widespread acceptance, and new low-power capabilities to compete with technologies that also want in on the IOT. These include ZigBee and Near Field Communication, both which are arguably niche technologies that just aren't familiar to many people.
As IoT looms larger for environments of all sizes, Bluetooth 4.1 allows client devices to daisy-chain to each other and multiple devices simultaneously for larger networks that are more Zigbee-like. Perhaps the biggest change for those of us who have to guide our network environments into the future: Bluetooth’s latest version lays the groundwork for dedicated device channels and the use of IPv6 for smart sensors to bridge themselves out of the isolated PAN world and into the IOT. This represents a major and substantial change to the Bluetooth mission, and will absolutely impact the Zigbee market in some substantial way.
Other features with Bluetooth 4.1 make it generally better in its PAN role. Bluetooth has been improved to ensure that nearby LTE radios (frequently under the same device hood) are not interfered with. It has a longer allowable interval between service advertisements, for better battery life and less chatter in the busy 2. GHz band. One of the big gains with 4.1 is the Bulk Transfer feature. For example, the feature would allow my fitness gizmo to auto-transfer all the data it's recorded of my gym activities when I get within range of my cell phone to update the app that tracks my activities.