For one, I personally have more than one google account, one for porniness, one for everything else; I also have a separate user account on my computer for porniness so it's really easy to keep the two google accounts separate but still, the article omits that possibility or passes over it with hand waving. Yeah, as I'll even admit, it could get tricky if I didn't already have separate user accounts; I made the second account specifically to segregate that part of my life and make it inaccessible to others--ie, private. Private things kept in their private place. (I also separated that out to make it harder to give in to temptation; having to log out and log in to that user is sometimes enough to derail hardcore masturbatory timewasting.)
One thing I don't understand is why people are complaining about a unified user-id-ness. Yeah, I get how you might not want such-and-such information being visible to so-and-so, but frankly I've always lived as transparently as I could. If I were you, I'd ask: Why am I ashamed of this part of my life? Granted, as I've gotten older, I've come to appreciate wanting to keep somethings less visible. Certainly, certainly. I also understand that some people are much touchier about their infoz than I am. Certainly, certainly. Ultimately, I don't want to get involved in the debate serioulsy enough to engage those concerns. I just wanted to point out that some people don't feel so touchy.
The last thing I want to point out is the usefulness of this move. For those that aren't google fags like me, once you're logged into a google account it tends to follow you around the internet through its various services. But here's the thing: that particular feature of it doesn't creep me out, I find it extremely useful. I'm grateful that I can be in my gmail writing an email then hope over to google calendar to check availability and sidle over to google maps to make sure I have enough time to get there in time and then pop on blogger to talk about it; the less I have to stop and log in between each of them the better. Plus, I do believe Google is trying to help not herd us (laaaawl, punz).
An important but I think too easily dismissed point is how their goal has been to simplify their privacy policies. This article from The Atlantic explains what a bitch and a half actually reading every privacy statement on the web would be. Google's reason for changing their privacy policies is simplicity. In light of The Atlantic article, that's actually a pretty big deal; it would take a long ass while to read 60-odd separate privacy policies (with likely many redundant portions) when now you can read just one. And yet everyone seems to dismiss this as frivolous or even spurious rationalizing before they dive into how violated they feel. Granted, their feelings of violation are theirs to feel, but at least now they can find out about it much more easily--by referring to a single policy instead of 60.