A Google Groups thread has discussion on the topic of dynamically creating pages to target localized searches. For example, this particular webmaster wants to be able to target 28 different zip codes for his client’s A/C business. He summarizes what he wants to do:

This was a popular SEO tactic years and years ago. These days, it is much harder to rank well for terms using the automated city database methodology. We actually covered some of the databases you can purchase to accomplish this back in 2005. But is this legit?

According to Google, no it is not. In fact, Googler, Reid, said that the manner in which this webmaster wants to go, seems to be a “doorway page.” Reid said:

Your best bet in this situation is to create useful and unique content for each page. How? Well, take a look at some of the major local portals and see how much effort they put into their localized pages.

But would you consider these to be doorway pages? Google defines a doorway page as:

Forum discussion at Google Groups.