Google has now formally launched its mobile 'product search' system for users in the UK, USA, Germany and South Korea. I've put some screenshots below - essentially you can type in any product (e.g. while standing in a shop) and get a bunch of the best deals from around the web. In Web, go to (or create a bookmark for) www.google.com/m/products or www.google.co.uk/m/products (or similar for Germany and S.Korea).