One of the excellent new features of the Raspberry Pi 3 is the built in bluetooth. If you are already running a set up OS and do not wish to start over again you can install the drivers to enable to feature manually with apt-get
Note, I am on raspian Jessie, I do not know if this will work for older wheezy users.
sudo apt-get install pi-bluetooth
This will install the appropriate driver for the pi 3 and once it is done setting up you should see something similar to this:
pi@retropie:~ $ hcitool dev Devices: hci0 B8:27:EB:C0:D7:C1
From there you can pair your bluetooth devices as normal.
This is a great upgrade to the Pi as it not only saves you $20 between a bluetooth and a wifi adapter but you also reclaim 2 USB ports.