From a post on XDA
Ray Maker of DC Rainmaker on Twitter reports ANT+ is coming to the Samsung Galaxy S4 through an October Firmware update and will be supported on all flagship devices going into the future
dcrainmakerblog
"We will support ANT+ in the Galaxy S4 in a firmware update coming in October" - Samsung (at the ANT+ Symposium)
dcrainmakerblog
"We do plan to support ANT+ on all of our flagship smartphone devices in the future" - Samsung (at the ANT+ Symposium)
Particularly for anyone with sports data tracking devices this is huge news! Not to mention ANT+ is pretty simple to implement now with the new Plugin services they're bundling with the Note 3 right now
ANT also allows you to build really neat wireless topologies as well if your into that stuff, plus it supports full multicast as seen on DC Rainmaker
Curiosity/Survey: Do you use a different device for running than cycling? | DC Rainmaker
A little background on ANT and ANT+:
ANT is a mature ultra low power wireless protocol running on the 2.4 GHz band like WiFi and Bluetooth. Bluetooth Smart is a protocol similar to ANT but architected around Bluetooth style bonding/pairing with several connection layers and services.
ANT is a compact and flexible protocol, allowing virtually any type of wireless network topology to be created. ANT transmitters automatically manage coexistence and divide the RF channel they are transmitting on into timeslots, which means any number of receivers can listen to an ANT device, excellent for gyms, training areas, anything which requires a large number of transmitters, as ANT can handle potentially hundreds of devices transmitting to an infinite number of receivers.
ANT+ is a set of interoperability specifications called "Device Profiles" which means devices which use them are able to "talk" to one another. ANT+ has reportedly shipped in over 60+ million devices globally, predominantly in Sports and Fitness (Adidas miCoach, Garmin Watches, Running Sensors, Heart Rate Straps, etc).
Why does this matter?
Right now, it only matters if you're into any type of sports or fitness training, or if you have an idea which requires 600+ transmitters communicating to XXX number of receivers simultaneously. As a nice bonus, any ANT+ device is compatible with any app as long as it's certified.
Some Apps which include ANT+:
-Google My Tracks
-Endomondo
-Garmin Fit?
-Run.GPS Trainer UV
-IpBike, IpWatts, IpPeloton, IpSmartHr
-Selfloops
-SportyPal
-MapMyFITNESS/RIDE/RUN/WALK+/HIKE/DOGWALK
Directory of Certified Devices
THIS IS ANT - Directory
Oh and there's a comparison here
THIS IS ANT - ANT+ / BT Smart Comparison
Basically it's similar to Bluetooth Smart but supposedly more mature, simpler to use, and with much more flexible topologies and better RF density.