I've actually seen an increase, but I seem to be in the minority. I've seen quite a few posts about drops in earnings and a drop in views.
To Frankly My Dear: I believe the reason the ads are different than you hubs is based on what you have searched for. I noticed a correlation to what I was searching for recently in google and what ads would appear on hubs I was looking at. So for example: I had been researching lawn and landscape in our area earlier, than I got on to hubpages and was reading articles on SEO and I would see ads for TruGreen and Local lawn companies even though the hubs had nothing to do with them. I'm wondering if its a change in how google decides what to display in ads.