Matt McGee is just begging to be put on the speaker circuit for local search with his exceptional Guide to Local Search Marketing. Matt's done an excellent job of showing (not just telling) where results come from in the local and map search engines and helping marketers to navigate the waters at major local search sources:

Images like the one below are very helpful in understanding exactly which results can be influence and affected.

Ads on Google Local Search

Congratulations, Matt! This is a stellar bit of work and something that I'll make sure everyone at the office reads through.