[tor-talk] google analytics says it can track across separate domains

[Joe Btfsplk]

A few months ago, someone raised the question of TBB or any included 
addon not blocking web beacons / trackers and perhaps something like 
Ghostery should be included in TBB (I think).  I asked about beacons 
(web bugs) compromising anonymity (not to mention privacy).  Can't find 
the post, but I believe either Mike or Roger replied that it shouldn't 
be an issue because web beacons, like Google Analytics, can't track from 
site to site.  Hope I've got the essence of the reply correct.

That didn't sound quite right, so eventually looked a bit more.  I'm not 
quite sure what to make of this, but doesn't sound good.
 From this Google Analytics site 
https://support.google.com/googleanalytics/bin/answer.py?hl=en&answer=55503

> "This article explains how to track across completely separate 
> domains, like www.example.com and www.mysite.com."

And from the later version of Google Analytics, 
https://developers.google.com/analytics/devguides/collection/gajs/methods/gaJSApiDomainDirectory
> |"_setAllowLinker(bool)|  Sets the linker functionality flag as part 
> of enabling cross-domain user tracking."

There are other independent articles I've read about ability of web 
beacons to track across sites.  Here from the horse's mouth, * seems * 
to be verifying in a matter of fact, ho - hum way, they can & do track 
across completely separate domains.  Unless I've completely misread it.

I don't know what this means to Tor users, but as a Firefox user, I 
don't want them - & always suspected they were capable of doing more 
than gathering data ONLY on the site where they were 1st loaded.  BTW, 
have many read the new Google "unified" privacy policy?