tedster - 9:02 pm on Jan 12, 2011 (gmt 0)
Everybody in Local Search is trying to understand that - it's a discussion better held in our Local Search Forum [webmasterworld.com].
The kind of SERP we're talking about here Google has called a blend of organic and local. For example, the listing may be the organic one but enhanced with a map marker or Place information. It's something that is currently changing faster than you can type up your observations. Google's Marissa Mayer was put in charge of it, and she seems to be stirring the pot regularly.