Think of it as a bar code for marketers. Using a QR Tag Reader application for your Smartphone, the tag is scanned by taking a picture of it using your camera via the reader application. The application then connects to the Internet to decipher the tag.
The tag at right, when deciphered, contains the name of my company and contact information.What you put into a tag for your business could be a coupon, a link to a webpage with interior pictures of the house you are trying to sell or whatever your imagination comes up with.
For your Blackberry, I recommend QR Code Scanner Pro: http://appworld.blackberry.com/webstore/content/13962
To create your own QR Tag, try Kaywa QR Code Generator: http://qrcode.kaywa.com/