The other night on "invention" or some such program was a 5 minute blurb 
about the process used to make Guinness Stout from a can look and taste like 
Guinness Stout from a Pub. Anywho, the short of it is there is a small 
nitrogen bladder in the can which releases its stuff when the can is opened, 
and when the contents of the can are poured into a tall 16oz glass, VOILA, 
you have the classic Guinness head.

So while sorting thru the microbrews down at the local beer emporium, I saw 
a can of the stuff...bought it....and popped it open. They were right! Its 
amazing...just like out of a keg. Sort of gives the phrase "getting a little 
head" a whole new meaning!!  ;-)

For those who are interested its in a 16 oz can with the label "Pub Draught 
Guinness".

Enjoy!

Ric