Smart merging of technology and advertising here, whether you're at the bar or at home enjoying a pint. Pour a Guinness inside one of these special glasses and the QR code pattern is revealed...
"Scan the code with your smartphone, and it "tweets about your pint, updates your Facebook status, checks you in via Foursquare, downloads coupons and promotions, invites your friends to join you, and even launches exclusive Guinness content."
Via AdWeek

Commercial Flour Sa...
While I love the idea of QR codes being used more often.. it really is best to know where the QR code is going to take you before you scan it.. perhaps there is some small print on the glass somewhere?..
Cute, but utterly pointless. I'm not really so keen on this when www."site desired here".com would do the same trick.
"Pour a Guinness inside one of these special glasses and the QR code pattern is revealed"
or any other dark beer...