I think this is a good thing. I also don't think it is 'concidence' that the spam filters got 'turned up a few more notches' recently. Think about it. If the spam filters drive 'SERP spam sites' out of the index - and it forces them to give Google their money - for a well documented 'paid placement' with defined rules - instead of giving the same money to their 'spam consultants' - then who wins?
The spam consultants - well - they lose;
The honest webmasters (who adhere to the letter of the Google do/don't published guidelines)- win (as the spam around them dissipates);
The 'joe public' searchers - they win too (as they won't find casinos when they search for 'chocolate fudge'); and
Google - it gets more money (which - lets face it - it deserves for creating a great SE).
Looks like a sound business model to me!! Hey GoogleGuy - you should have called it 'Robin Hood' Adwords!!!! : )