Google Product Search was already useful, but the addition of local inventory info makes it even better still. The new feature works on the iPhone and any PalmOS or Android device. Just search for Shopping results and Google will return not just pricing information for the item in question, but it will tell you which retailers have it nearby and whether they’ve got it in stock or not.
That saves you a trip and the cost of gas. The problem right now is that only a few retail partners are signed up. There are some major ones like Best Buy, Sears, and Williams-Sonoma, but the feature needs more participation from both big stores and local merchants. We are sure that will happen given some time.