Directions Magazine has an article by Adena Schutzberg and Tina Cary who investigated what 216 companies in the geospatial industry tweeted during two days in 2011. The total number of analysed tweets amounted to 430.
The gist of the results: The majority of tweets were sent out in bulk, there was only limited interaction with other tweeters. However, the situation improved from 2010 when the companies used Twitter almost exclusively for broadcasting. Still, the biggest proportion of tweets was about the company tweeting, not about customers, users, partners. So again, no interactivity, non-social social media usage.
Head to the Directions Magazine for full coverage.