This is almost the case. The POSTNET (and I think PLANET) bar codes you find on delivered envelopes are encoded with the 9-digit zip code, a 2-digit delivery point code, and a 1-digit check code (which can be calculated yourself). You can find the 9-digit zip code and the 2-digit delivery point code via the USPS web site. (The 2-digit delivery point code will be in the Mailing Industry Information link to the right of the results display. It is usually the last two digits of the street address number or box number.) With just that information (and calculating the final check digit), you can create the POSTNET barcode which is unique for each deliverable address.

Now, if I could just figure out how to use the approved pre-sorted postage of only 32¢ when using these barcodes, I would be a very happy person.