Avoid these shysters like the plague - after all, if they were so good at getting backlinks, why does google only show 3 for their own site? And yahoo only a few hundred?
This is a classic sting - a site manages to claw its way to 500 useless backlinks on blogs, forum spam etc, and then decides to capitalize on it by trying to sell its worthless services to inexperienced suckers who are too trusting for their own good.
Not that my friend would fall for it, of course. he just wanted me to post it up here.