Phil Windley notes that the power balance between retailers and buyers is shifting - there are apps for the G1 (Google) phone and the iPhone that make it easy to instantly check just how much of a bargain the item in front of you is. A Phil relates, retailers aren't going to like this much:

Trying to fight instant price match is like trying to hold back the Mississippi. Retailers aren't going to be able to support artificially high prices based on information asymmetry anymore. I don't have an answer for them. But telling people they can't use their phone inside the store isn't going to cut it.