goodroi - 12:42 pm on Jul 24, 2013 (gmt 0)
Google talked about this in May ( [googlewebmastercentral.blogspot.com...] ).
To see this in action search Google for very well known public companies (please don't share specific keywords as per forum charter).
...Markup like this is a strong signal to our algorithms to show this image in preference over others, for example when we show Knowledge Graph on the right hand side based on users’ queries...
Google seems to be testing logos in the organic rankings using Google+.