so this has been kinda known for a while now to some but i thought I would share it anyways to help people understand that this is one of the ways FB pops your ad accounts if your not being careful....
http://www.foxnews.com/scitech/2011/...rivacy-breach/
as far as what type of cookie they are using and how persistent it is just doing the "clear all cookies" may or may not work.....
Not that they use this specifically, but it's a good idea to test your method of keeping your accounts isolated with http://samy.pl/evercookie/ to see if it can penetrate whatever barrier you create.
I wonder whether using different user accounts on a computer can shield you from this.
yes it probably would but evercookie is sneeky and works cross browser -> ie if I access the cookie page in one browser (ie Chrome), and then revisit in another browser (ie FF), it still works.
I know for a fact that facebook have employed similar tactics in their facebook connect plugins.
so my advice is to rely on a browser aoppliance.
You can download the free windows VM viewer from vmware + their browser appliance and you just restart it each time afresh 
Wow. That's probably how they caught me. Sneak sneaky dudes.
@polarbacon
is that separate account/separate cookie on WIN7 for both x32(86) and x64 OS versions ?
If so. 
heres the player for windows:
http://downloads.vmware.com/d/info/d...are_player/3_0
Here are some browser appliances:
http://www.vmware.com/appliances/dir...at/0?k=browser
heres a tutorial to build your own:
http://charlessocci.com/2008/12/15/a...ivoxy-and-tor/
Hey guys - bringing this thread back from the dead.. Do you think you can by pass these cookies by using private browsing in chrome? (uninstall and reinstall?)
Use Safari in private mode , it's the safest and doesn't pass any kind of cookie ( read on tech site case study ).
I use VirtualBox + Tiny XP. Then Clone the installation and use 1 FB account on each and only for Facebook, not for other browsing.
This is how you do it: http://www.pyrogenicmedia.com/instal...l-box-tiny-xp/