The WSJ's headline—"Apple, Google Collect User Data"—borders on art, but the real point of note from the piece as it attempts to corral and make sense of the sprawling issue of cellphone location data is that when Google collects data about nearby Wi-Fi hotspots from your phone, that data is apparently tagged with "a unique identifier tied to an individual's phone," and it's sent to Google "at least several times an hour."
It was uncovered by former MySpace-exploder-turned-security-consultant Samy Kamkar for the WSJ, which then verified his findings with an independent consultant, Ashkan Soltan.
Google says that the data is totally anonymous, but by tagging location data coming from each phone with a unique identifier, it does potentially map out a phone's—and its user's—movements, no matter how well-protected or otherwise anonymized Google's database may be, especially given the frequency with which Google's apparently receiving data from phones. (Versus, say, dumping all of the location data into a massive pile with no unique ID for any of the data, like Apple does—presumably, if Google's simply mapping Wi-Fi hotspots and cell towers, the data should be just as useful without the unique IDs.)
Update 1:17PM EDT: An official statement from Google, in which they insist your data is completely and totally anonymized—and they note importantly, if you don't have Location Services turned on, the data's never sent back to them: "All location sharing on Android is opt-in by the user. We provide users with notice and control over the collection, sharing and use of location in order to provide a better mobile experience on Android devices. Any location data that is sent back to Google location servers is anonymized and is not tied or traceable to a specific user."
Also! The WSJ may have been a bit disingenuous about the way they present this "unique identifier" business—Microsoft and Apple do the same thing, and all three companies say everything is completely anonymous.
So, uh, bottom line? Your phone, and a company or two knows where you are, if you allow them to. Just like yesterday, and the day before, and the day before that, and so on. [WSJ]