I’m not sure if OldAdmin had a reason for keeping it relatively separate (or even if New Admin might have a reason to want to), not my business. I remember at some point a link to the wiki would appear automatically at the head of some of the o/s threads eg Germany.
It’s not massive or perfect, but growing. It can be a useful starting point for some subjects and places, saving long repetitive answers in the threads and easier to print out if you’re going abroad.
Anyone can contribute — though I think you have to register — and entries can be text or links to prominent UKP information threads. As with all wikis, a less personal style is the intended norm, with reference material rather than individual reviews.
The new sticky seems a great step forward in my opinion.