US Retailer Target recently announced their smartphone based coupon program. Once you visit their website and Opt-In to the program, you will be provided with a webpage that has a list of deals and a scannable barcode coupon. 

Once you have seen where you can save some money, head to the checkout, display the barcode and the money will be deducted from your bill. 

Right now this seems like a pretty limited use, but the potential is huge. You could sign up to coupon sites, retrieve single use coupons for a variety of stores and save a tonne of cash. Retailers could track exactly who used the coupons and where to help better target their potential audiences. It's a win-win.
 

I think the potential here is huge, and I don't think this is a "fad" we will see disappear soon, I can see several stores and sites offering similar services in the next few months. Geo-target marketing is one of the fastest growing tools for smartphones and this use would yield valuable information about buying habits and trends.

No word yet on when we will see this at a Canadian chain, but keep your eyes open, because it will be soon.