Here's a couple thoughts. There is always unweighting of the skis when linking turns. Inherently, it has to be. As many have said, there are many ways of categorizing these patterns.
The fact remains there is a release of energy (rebound) and a period of the skis being light (unweighted) and then pressure again in a new turns. The beauty of skiing is the endless possibility for variation. No two turns are the same.
However, the core movements of sound skiing to link turns can be categorized and utilized on a regular basis. Bob B. (not suprisingly) did a nice job of listing the generally accepted forms of unweighting / transitioning.
I think it is a good goal to have the skis realease right straight up perpendicular to their surface under boot. Personally, I like the relaxation/retraction move to do it, so the upper body moves into the turn and the feet draw right up and out the other side with the inside foot lightly leading the edge change of the skis. Howerver, the skis don’t always do this becuase your skis always maintain forward momentum and they can shoot straight out from underneathe you. So...they do not always spring straight up, they can shoot out too whn you’re off balance.
Beyond this, we are engaging in a potentially lenghty but interesting discussion of the variations to unweight the skis. I firmly believe that good skiing is as much about taking weight off the skis as it is about on putting it on. But here's a couple more thoughts on a topic that has come up.
Rebound. Rebound, I believe (like others here) involves more then just your skis decambering. It also involves you standing on your skis resisting the G's of your turn. The G forces generated by you making a turn depend on factors like your weight, speed, turn radius, snow and terrain. The forces can be from nothing at all when sliding around with a beginner lesson to crush-you-into-the-mountain strong in a really high speed turn through, say, a transition from steep to flat. For the most part we all know our limits and ski within them.
The rebound comes from how we release the G's from the turn. How we choose to come out of turn and into the next. One example is if you resist all the way through a turn and push (extend) at the end to release and transition you can get a very explosive transition, fast lots of energy (rebound). But it does not come just from the bent ski. It comes also from you and all the pent up energy of the you and the turn and the you being stringer and pushing aganist the G's to up un-weight.
You can also gently guide the release of the energy (or inherent rebound) by relaxing your leg/s more slowly and "let the air out of the tire" to transition, so to speak. You can do this at a very high speed or low speed and transition very efficiently from one set of edges to the other.
So, I believe that "rebound" is defined by factors beyond just a decambered ski and that how the energy is released is one those beautiful endless spectrum aspects of skiing which we all dig so much.