The current kernel of Fedora 21 doesn't support the Wifi chip used on my Mac Book Pro. Proprietary Broadcom drivers are packaged and available in the rpmfusion repo.
Verify that your card is a Broadcom using:
lspci -vnn -d 14e4:
02:00.0 Network controller : Broadcom Corporation BCM4360 802.11ac Wireless Network Adapter [14e4:43a0] (rev 03)
Install the rpmfusion repo: http://rpmfusion.org/
broadcom-wl package from the rpmfusion repo, which will install kmod-wl, akmod-wl, and other dependencies.
sudo yum install broadcom-wl
Restart to enable.
At this time, the kmod-wl package (220.127.116.11-7.1.fc21) has a hard dependency on a specific version of the Kernel (3.19.1-201.fc21), whereas the latest version in the Fedora repo is 3.19.3-200.fc21.
The Koji project contains all previously packaged and released packages. To view Kernel packages, see: http://koji.fedoraproject.org/koji/packageinfo?packageID=8
Packages can be installed with
sudo rpm --oldpackage -i <rpms>
lsmodto list all kernel modules
sudo modprobe wlwill force the wireless kernel extension to load.
sudo systemctl restart NetworkManager