A couple of years back either MBR or WMB did an article on riding up it – Nick Craig, a guy from Hope, a Journo, and my mate Martin (rides for yeti). I think they all cleared it a couple of times, and Martin was going for a middle ring attempt – think he got within a couple of feet of the top.
I was there at that photoshoot. The rules were set out – no dabs, no holding onto walls etc. Trackstanding was allowed to check out lines/rest etc. Gates were held open. The riders were observed at all parts of the climb.
Martin cleared it on his Felt hardtail – I have to say he's one of the best and smoothest riders I've ever seen.
Nick Craig cleared it but it took a couple of attempts. He was on a Scott Spark. Paul Oldham didn't make it (although he did far better than most folk ever do).
Afer the challenge bit was done, they spent the rest of the time shooting different sections for the article.
It's worth pointing out that Nick hadn't cleared it in one go for the last 10 years and he hasn't done it since. Conditions on the day were perfect. Jacob's Ladder is one of the few proper legendary climbs in MTBing and it can be done by the very best, the problem is that lots of people claim to have done it or "know someone who has". Anyone claiming to have done it without a healthy racing history at Elite level is probably lying!