This is some cool stuff. It's pretty much a 2D barcode, which is read by your mobile phone using the camera. Their proposed app is that a URL will be embedded in the tag and then the phone will go to that website. But anything can be embedded in the tag and this could easily be a replacement for barcodes. I'm having problems finding a cheap, small, barcode reader that works well with my Treo. I currently use the Socket SD barcode reader, but it uses really low power and it therefore makes scanning very difficult. Something like this might work perfectly. Unfortunately, the Treo camera can't be programmatically accessed, so therefore this technology currently doesn't work on it. But I'm sure a solution will come out soon. Here's the url for semacode - http://semacode.org/. There are a couple of other competing technologies as well - ShotCode, ColorCode and QR Code.