The latest blog entry at Inside AdWords is named Landing page quality update. The blog entry describes, in short,
Thus, over the coming days a small number of advertisers who are providing a low quality user experience on their landing pages will see increases in their minimum bids. It is important to note, however, that the vast majority of advertisers will not be affected at all by this change, as they link to quality landing pages.
Is this targeting sites specifically made for AdSense? AdSense arbitrage? Well, I am sure we will hear about it in the forums shortly. JenSense has her thoughts here, she looks into the possible changes but ultimately, it is a wait and see type of thing. There are so many factors that can impact pricing, it is hard to say the level of impact it may have on MFAs and AdSense arbitrage.