When I built my Mac Pro 3,1 machine (Early 2008) back in the day, I chose not to get an Airport Extreme card since I only intended to connect it via an Ethernet cable. However, I've noticed that the new Yosemite Handoff feature apparently requires not only Bluetooth 4.0 but also 802.11ac. Find great deals on eBay for apple airport extreme card for mac pro. Shop with confidence.
Mac Pro Airport Card
The Airport Extreme upgrade for the Mac Pro is not what most people would consider a card, since it doesn't go in one of the PCIe slots. It is, in fact, a card similar to that which goes in a notebook computer. Most internal wireless cards for notebooks are mini-PCI or mini-PCIe and fit into a miniature card slot inside the computer. The Airport Extreme card for the Mac Pro is the same type of card. It is not as easy to install as a typical PCIe card, but no more difficult than adding RAM. The hardest part is the antenna connection and cable routing. I installed one of these in a Mac Mini last night (much more difficult than the Mac Pro) and it took about 15 minutes. It took 5 minutes to add a similar card to a Dell Notebook computer, and the Mac Pro should be about the same or easier.