The following was taken directly from the Google Local Business Center help page. I highlighted some of the more interesting information for discussion. Please read what Google has to say about how your business ranks, and if it is going to show up in the 10-pack carefully.

Ranking of listings

All Google search results are based primarily on relevance, and Google Maps listings are no different. Google Maps ranks business listings based on their relevance to the search terms entered, along with geographic distance (where indicated) and other factors. Sometimes our search technology decides that a business that’s farther away from your location is more likely to have what you’re looking for than a business that’s closer.

Google Maps and the Local Business Center are a free service, so there’s no way to request or pay for a better ranking. We also can’t provide additional details about our ranking algorithm. We do our best to keep the details of the algorithm confidential in order to make the ranking system as fair as possible for everyone.

Here’s the take away.

Local Search Results are based on relevance.
So, how can you make you business listing the most relevant result for the searcher?

Relevance is associated with the search term entered.
What does that tell you about the categories you select and the page names and content that you have on your website or blog?

Google is hiding their algorithm from you.
This is where we come in. We spend day and night researching and reverse engineering what Google is doing with their algorithm to help you make your local business listing the most relevant business listing for the searcher. Our job is to take our understanding of this algorithm and help you get to the top of the 10-pack.

There are four parties that want you to be the most relevant result.

1. Google wants to show the most relevant result
2. The searcher wants to see the most relevant result
3. You want to be the most relevant for a specific search term
4. And we want you to be the most relevant result for your specific area of expertise