Haven't seen this discussed anywhere else, but I've been noticing some small but significant tweaks in how Google's presenting its search results. (It's true that Google is always fixing this and changing that, but these are particularly interesting, have persisted for several days, and show signs of sticking.)
As part of its Universal Search, Google has been pushing at its users all sorts of content -- video, shopping, review snippets, blogs, "real-time" feeds - to the point that cracking the top page was becoming all but impossible. For some terms, the "top 10" had become the "top 3," with most of them below the fold. SERP pages had become pretty chaotic and less than useful.
But over the last week or so, Google has been going back to SERPs that look more like they did 10 years ago: overwhelmingly textual. (The font size is bigger, too.) If you want to see the other stuff, you still can; just navigate in the left margin.
The tradeoff is that it's harder than ever to get a "pure" search without personalization. Even if you're logged off and your detailed search history is unavailable, Google will try its hardest to customize the search by your IP address, location or cookies previously set in your browser. That all makes a search professional's job that much harder; too many of us try to justify our existence by providing clients with SERP position, as if that position proved much of anything. Worse, there's no really clear way to be sure that positions pulled using tools like AWR or WebCEO are "pure," because Google could be finding ways to "customize" those results.
Best answer is as it always has been: judge results not on SERP position but on traffic. And if you're really hardcore (which you should be), judge your results not just on traffic, but on traffic that converts. Of course, that requires clients to understand what a valid conversion is, but no one said this job was going to be easy....