The next time you Google something, if the search results seem a little too good, a little too personal, it's because they are.
While Google's always delivered customised search results to people logged into their Google account—that is, search results tailored to you, based on your web history (yes, even outside of Google, like Gizmodo), past searches and previous results you've clicked on—it's now going to be doing that for everybody. Even if you're not logged in, you're going to get personalised results and yes, more targeted ads, based on past searches, tracked by an anonymous cookie that stays on your computer for 180 days. (BTW, it's not like Google's just started keeping track of your searches, it's just now Google's using that info more directly, that's all.)
You can turn it off here, though I'm guessing that won't turn off the dirty feeling you've got right now.