Ooh, my sister got her boyfriend one of these for when he goes mountain biking. Can't remember what it was called but I'll ask her to log on so she can let you know.
We've used it snowboarding, mountain biking and climbing (I haven't done anything interesting enough on the horse yet to warrant taking it out!), and it will be coming climbing with us to Spain in Feb and surfing in April.
It is v good - battery life is OK bearing in mind how cold it was boarding, only minor disadvantage is no screen to see whether you are pointing it in the right direction or not, but TBH the wide angle lense more than makes up for it.
In terms of being waterproof, it certainly puts up with wiping out on the slopes and snowfall!
BTW I got mine at Olympia and they weren't exactly doing a roaring trade so I got one with some extras thrown in and money off too - if you're going it might be worth seeing on the tradestands list if the company will be there!