Since WikiLeaks released 250,000 secret U.S. government cables a little over a week ago, the world is suddenly terribly concerned about what we may or may not be reading. Some countries - and some U.S. government agencies - are blocking their people from accessing the Wikileaks site, for fear of reading.

So the EFF's E-Book Buyer's Guide to E-Book Privacy comes at a good time - not just for holiday shopping, but for those of us that want to read that other famous trove of classified materials, The Pentagon Papers (or, okay, perhaps read other things too) with some assurance of privacy.

EFF's guide provides a review of the privacy policies of various e-book providers - both hardware and software makers - from the Amazon Kindle, to Google Books, to the Internet Archive. The report is based on what the policies say themselves, not on how they're enforced in practice.

Who Tracks Your Book Searches?

Google Books logs all your search data with an IP address and will associate searches with your Google Account if logged in. Amazon also logs data about what you've viewed and searched for. The privacy policy for the Nook isn't clear, according to the EFF, but Barnes & Noble logs data on searches made and pages viewed on its website.

Who Monitors What You're Reading?

Google logs the books and pages viewed, and while Amazon does too, EFF says that the "exact parameters of information logged in unclear." It's not known if the Nook monitors your reading after purchase. But the other 5 e-readers in the guide - Sony Reader, FBReader, Internet Archive, the iPad, and the Adobe Content Server do not.

Who Tracks What you Buy?

Again, Google and Amazon track the purchases you make on their sites. The privacy policy is unclear for both the Nook and the Sony Reader. The iPad will keep track of purchases made on the iBookstore and via other Apple apps, but otherwise no.

With Whom Can This Data Be Shared?

The Internet Archive, FBReader, and the Adobe Content Server do not collect user-identifying information. For the other companies in EFF's guide, law enforcement and civil litigants may get access to data, as required by law. And Google, Amazon, Barnes & Noble, Apple and Sony all share information within their own products.

In order to share information outside the company, users must opt-in with Google. Users may opt-out of having their information shared by Amazon, Apple, and Barnes & Noble for certain promotional and marketing purposes.

Can You Delete Your Data?

If you have purchased an e-book, in most cases deleting it or disassociating it from your account means - no surprise - you lose the ability to read the book. Google does allow you to remove book titles from your account and delete your search history. But other vendors do not allow you to access or delete parts of your search or purchase history.

Does It Matter?

The data that many of these e-readers gather does help them deliver a better experience in a lot of ways. iBooks needs to track the last page you've read, for example, if you expect it to be able to sync across devices. Amazon tracks what you search and purchase in order to make suggestions for items you might like.

But one's reading habits, perhaps because reading has been such a private endeavor, have typically been closely guarded. We may want to disguise the fact we never finished Ulysses (I confess). We may want to disguise having read all the Twilight novels - twice - (I haven't, I swear) or having a penchant for really low brow science fiction (no comment). And of course, we may want to read books that are politically unpopular.

You can read the full guide here.