Yesterday M+R Strategic Services released their 2010 NonProfit Social Media Benchmark Study: An Analysis of Growth and Social Engagement Metrics for Nonprofit Organizations. This is coming from the same company that has performed similar case studies on email use for nonprofits (2008 & 2009).

The findings in the study, while not all that surprising, are quite re-assuring for some of the best practices we already know. 

Below are a few of the highlights:

• Organizations posted to their Facebook Pages an average of six times per week and tweeted four to five times per day.
• Each week, an average of 2.5% of each organization’s Facebook fans took action (e.g. contributed wall posts, “likes,” or comments).
• Facebook fan bases grew by an average of 3.75% each month, and Twitter followers grew by 9% per month.
• 2% of Facebook fans removed themselves or hid their news feeds each month.
• Facebook fan growth occured at a rate of 0.23% for each post by the organization.
• For every post by an organization, 0.56% of that organization’s fans viewed the Page 

A deeper read of the case study talks about the different types of organizations that were used for evaluation of Facebook and Twitter as well as a look into money raised via the 'Causes' section of Facebook.