Purchasing mounts through the Battle.net store will give you an option to either use the mount on your own account, or give the gift to a friend. Selecting the gift option will generate a code, which you can then toss at the recipient to use at their leisure. All they have to do is log into their Battle.net account and redeem the code by going to the Games & Codes dropdown and selecting Code Redemption.
While it's nice to see the Skyreaver added to the Battle.net shop, it does make one wonder if the in-game store will see gift-giving functionality eventually added. With how easy it is to use the shop interface, it would be nice if it generated codes as well. Hopefully we'll see that at some point in the future.