Interested as well, but I'm still not sold on the dropper idea. Maybe I just don't ride enough downhill, or my seat is too low to begin with, but I never have a problem getting off the back. I guess when the seat hits me hard in the stomach I'll decide to try one out.
I've got a photo of Catharine Pendrel doing the rock drop in Kabush Falls at Windham from this past weekend, she's got the saddle at full height, and she's WAY back, almost hitting the back tire with her butt, the saddle an inch from her chest. I'd post a link but I haven't uploaded them anywhere yet.
Tanja Zakelj had been running a dropper post last year, but when we saw her at Windham, it was a standard post.
Mind you, what World Cup XCO racers do on their bikes doesn't have much to do with what we should do, just thought of them. Apparenly last year Nino Schurter won a bet against some of the Red Bull Rampage style riders by riding a particular trail with no dropper post on his XC race bike.
I see the point of the dropper post, but for me I'm just so used to riding with it at XC height, it feels strange. Quite sure if I spent the time to force myself to learn it, the benefits would be real, so I won't poo-poo them quite yet.