"Private email messages might contain any number of personal, embarrassing or otherwise damaging information," Blumenthal wrote. "Google's attempts to amplify and contextualize this information through targeted ads, maps suggestions or calendar reminders could have negative consequences for users."
Cohn also says she's troubled that Google users can't create anonymous identities on Google services if they want to keep their anonymity online and not have Google know what they're doing through all facets of the Web.
"If you're in the United States or Europe and you're worried about a government investigation of your email or search history, Google is not such a safe place for it," she says. "The answer should be that Google lets us create truly separate identities on these services."
Another concern is that users may not want to have data from their emails - which are often very private - amplified on other Google web pages. For example, let's say that you're due for heart surgery and you've been emailing frequently with friends, family and doctors about it in an attempt to get both information and moral support for what you expect will be a trying ordeal. Do you really want to go to your YouTube page and all of a sudden see that Gmail has recommended a bunch of videos of open-heart surgery?
"I consider information... to be like pieces of rock in a mosaic," explains Pete Hickey, a student at Ottawa University. "Individually, each little piece doesn't mean much, but when you get enough and put them in the right places a nice picture emerges. Consider for example, Google Analytics. A large number of web sites use this, because it provides the developers free statistics on users of their web site. It also provides Google with information that you have been to that web site... a non-Google site. Their maps are the same thing. A site using Google Maps to show their location provides Google with information about you."
The Atlantic's Sara Marie Watson writes that one consequence of Google's new cross-platform information sharing is that users might be more careful in the future sharing their information exclusively over Google since they may not want the company to keep track of everything they do online. The trouble is, she says, that Google's multiple services have already become integral parts of surfing the Web, making breaking away from them a difficult endeavor.
"Personally, I'm inspired to find ways of disentangling myself from my complete and utter reliance on Google products," she writes. "It's the kick in the pants I needed to export my bookmarks and switch back to Firefox as my default browser. And perhaps I'll start uploading new pictures to Flickr... But I'll admit, I won't be giving up Gmail or moving my searches over to Bing anytime soon. I'm not calling for a boycott by any means, I'm just looking for a little more critical public discourse on our data."
Sign up for CIO Asia eNewsletters.