It's the adverts yeah. Some people think they can make a fast buck by creating a very quick n easy site, then piling it with adverts.
Quite often you see posts from well known blogs appear on these sites, or a popular viral image. I think this is the first time I've seen a set of actual valid links, but the principal is the same.
I don't know if they'll actually make any profit. After the cost of getting hold of a spambot and the time taken to find places to spam, I don't know if enough people will click an ad to make it worthwhile. And then there's always the chance that Google will close their adwords account before payday. I haven't read the adwords TOS recently but I would imagine there's something in there about spamming in order to attract ad clicks (which is possibly why they use PMs rather than posts that google staff could easily find)