802.11ac is the next generation of the wireless networking standard that is used in nearly all computers, peripherals, and smartphones. The ac revision to the standard provides an impressive performance boost of up to 1.3 Gbps, at least under ideal conditions. Your real-world performance will of course be less. But in this case, less is definitely more.
The current standard that Apple and most computer manufacturers use, 802.11a/b/g/n, provides data transmissions at up to 450 Mbps. Making the move to 802.11ac has the potential to triple throughput.
The advantage to Apple is in bragging rights (my network is faster than your network). More importantly, the ability to stream data using AirPlay and other Apple technology becomes even more enticing. 802.11ac should allow you to stream movies, music, and other multimedia content from one Mac or Apple TV to multiple devices, with no stutter or interruptions.
So, is Apple going to bring 802.11ac to the Mac? The answer is, of course it is. The real question is whether we'll see the high-speed wireless network standard this year in new Macs and AirPort updates. If you can believe the folks at The Next Web, the answer is yes, indeed, and the partner providing the necessary wireless chips will be Broadcom.
Just between us, I think The Next Web rumor may be a good one; I certainly hope it is.