The site hasn't quite reached the ambitious heights I had in mind for it when toxi and I first put the wiki together and drafted the contents. Some of the hack suggestions are out of date now, and many of the existing hacks don't work with the latest release yet. That said, I hope to put some time towards kicking it into shape over the upcoming weeks and I'd be delighted if you'd join me.
I should also mention that there's a good incentive to get your hacks written up, because we're planning to move Processing Hacks to processing.org - you might have seen a note about that in the Learning section. Fame and fortune (or at least some geeky glory) await!