I hope OS 11 is after Mountain Lion.
OS X is just starting to feel un-refreshed and unvarying. It's time to do to OS X what OS X did to Classic. Turn the old environment into a Fisher-Price playpen and give users a wholly new feel to computing. iDevices seems to be the trend. If Apple does their magic and combines Mac OS and iOS into something that's universally satisfying for both advanced and novice users, it will steal away a lot of alternative OS users.
The one thing that would absolutely put me in the line at the Apple store is if they named it after snakes. Python, Cobra, King Cobra, Viper, Boa, Taipan, Mamba, Copperhead, Krait, Bardick, Adder, Black Adder, Diamond Back...
Problem is, that some snakes have been used in the computer realm, such as Python and Taipan, etc.
Everybody hopes and speculates about OS 11's naming scheme, but let's not forget that the only reason we, the public, even recognize the big-cat names is because the internal code names became popular. I'm certain that Apple never intended for these-names to be marketed, as evidenced by OS X 10.1's lack of mention of Cheetah on any and all marketing material and the OS itself.
As with iOS, they will likely prefer not to assign any trivial naming scheme to their software beyond code-names.
[I still want to be first in line for Cobra]