Thanks Jamie - black hat, yes, but this method is going to start becoming the norm.
Once G started penalising sites they'll start hitting back. I would never have even contemplated this 6 months ago - but now with so much shite above my SERP because of sites doing this type of thing - plus G getting it 'wrong' - means I'm now contemplating abusing the system just like everyone else.
In the end it'll come down to black hat methods like this becoming the new SEO norm. Everyone will doing it and G won't keep up.