I've looked at Google's map API, which is all javascript and terribly slow on the iPhone. I then tried using the link option available at maps.google.com. That is fast but I can't see having much control over it. It also displays a little search box at the top of the map. Google's API says you must use maps in a website, which the iPhone isn't. I'm not sure about licensing for maps.google.com.
Urbanspoon's scope option does everything I want with maps in regards to displaying nearby businesses based on your location. Given the limited set of tools available for Google maps without mapkit, I don't know how they are doing it. It looks as though they have somehow integrated with mapkit. Clicking an annotation shows the callout and another click pushes a new view with details from that pin. Any ideas how this can be done?
-- EDIT --
Just to be clear, mapkit doesn't display surrounding businesses. That's the crux of the problem and I'm not sure how Urbanspoon got past it.