Well it seems that PayPerPost isn’t unique as a few other people are jumping on the bandwagon.
One of the notable ones is ReviewMe from the people at TextLinkAds. Although the theory is essentially the same as PayPerPost, the implementation is different. In PPP advertisers list opportunities which bloggers can the accept. The price paid ranges from about $2.50 to $10 (with the most common being $4 or $5).
ReviewMe works the other way round. Bloggers list their blogs with a price (determined by ReviewMe) and advertisers choose which ones they want to review their product or service. The price paid is dependent on the blog (how exactly they determine I’m not sure but it seems to be some sort of PageRank, Alexa, back-links type combination) and seems to be significantly higher. Of course you’re likely to get fewer offers though.
One offer they seem to be giving to everyone is to review ReviewMe itself (eerily like this) so every blogger accepted should earn something from them. And although I didn’t look at their payout details specifically, I would guess it’s the same as TextLinkAds - at the end of the month by PayPal with no minimum (and possibly other options with a minimum or a fee).