Yes, I have noticed similar. Have cancelled out some campaigns because of the cost of Adwords not being worthwhile.
Haven't you noticed? Almost all Google's latest changes seem related to shifting traffic and revenue away from the sites producing the actual content, over to Google sites, at any cost.
a) Apparent Adwords matching changes to increase Adsense display frequency across sites. (matching the highest number of destinations)
b) Google Preview. Keeping users close to the search page ad sections, so they do not have to pay Adsense revenue share. I get visited constantly by Google Preview, where they snippet out my content and show it on the preview pages.
c) Prioritizing Google Products, where Google gets the affiliate share.
... so on, and so on.
Anything to drive up their own profits, and take over what they can see might be profitable businesses. Google Products (taking traffic from NextTag, The Find, and others), Google Places (Yelp and others).
Search for any product, and Google Products links "shopping results" will be front and center on the first page search results, directing users straight to Google's own affiliate product site. Other search sites, such as TheFind and NextTag used to show in results, but have now been eliminated. (I think since Panda.)
Thats why last year they were called for an initial US Senate anti-trust hearing. (See [judiciary.senate.gov
...] and [nytimes.com
...] with other complaining CEOs testifying. I watched part of it on CSPAN.
More specifically I have noticed a shift in traffic, where a technical site (interesting only to geeks and admin types) suddenly gets the most traffic, because those searches on Google attract few ads on the search page, so Google is not interested. Also indicated by the fact that any Adsense resulting on sites are low-bid ads (for obvious reasons), with often only a 1-2 cent revenue share per click.
Notice, that we (web-site owners) are usually friendly enough to Google by providing them ALL the information they need to detect profitable areas to take over, by using Google Analytics and Adwords, and often the very convenient conversion tracking tools. Sending Google all the information they need to know exactly what amount of revenue is available in each business area they might decide to "take over".
We are our own worst enemy. :) Providing all the necessary information directly to our largest competitor.