3 posters for the same show, each one with a different QRcode. Scan the codes using a qrcode reader for your iphone or smartphone to reveal 3 different pictures. Decipher the 3 pictures to reveal the message. If you are a Mogwai fan it's fairly simple to figure out.
As far as the kanye comment, I hadnt seen it (i probably wouldnt have made these if i had) I've seen it now and as far as i can tell it was only used on a billboard - visually similar as these barcodes dont change much but a typically standard usage of them (as far as i can tell you link to a website and get a text message)
I like to think of this one as a sort of mini internet treasure hunt.