If OS X hasn't advanced as much as people would like, I suspect that has a lot to do with iOS sucking up a large portion of Apple's developer resources. Howeve

If OS X hasn't advanced as much as people would like, I suspect that has a lot to do with iOS sucking up a large portion of Apple's developer resources. However they are over that hump and over the past 2 years with Mountain Lion they're moving faster on OS X than they have in the past. IF they keep to what they said they intended to do, we'll have the follow on to Mountain Lion announced pretty soon.