Google and other advertising companies have been following
iPhone and Apple users as they browse the Web, even though
Apple’s Safari Web browser is set to block such tracking by
default.  How have they been able to do it? Well, first they
made Safari think the user was submitting an invisible form
associated with the ad.  That technique allowed the companies to
then place a “cookie” – a small text file that is stored on the
user’s computer and can be used to track online activities.
Google disabled its code after being contacted by The Wall
Street Journal.   Google’s code, which was placed on certain ads
that used the company’s DoubleClick ad technology and was
uncovered by Stanford researcher Jonathan Mayer, took advantage
of this loophole, as did the code used by the other companies.
In Google’s case, the code was part of a Google feature that
allows its “+1” button to be embedded in advertisements. Wall
Street Journal technologist Ashkan Soltani analyzed the code
further and found that 22 of the top 100 m