Science behind Guinness' cascading bubbles

I enjoy watching a freshly poured Guinness almost as much as drinking it!   I think of it as a lava lamp with drinkability.  You can approximate this effect by adding additional pressure to homebrew kegs but you risk over carbonation which can really effect the flavor profile of your beer.  The real magic happens when you step up to a Nitrogen and CO2 mix for beer gas which creates much smaller/tighter bubbles.  That's what Guinness does, to the extent of including that clever widget in their draught bottles and cans which release additional nitrogen when you open it.

So why do the bubbles seem to defy the laws of buoyancy and cascade down the side of the glass?  This episode of NPR's Science Friday explains the phenomenon quite nicely...  -D