Three-quarters of all software developers belong to at least one social network and two-thirds belong to two or more networks, according to the results of a survey released Wednesday.

Evans Data's Developer Relations Program annual survey of more than 400 software developers examined the dynamics of Web sites aimed at software developers.

"This latest research shows that developers are like most active Internet users in terms of having a very healthy interest in social networks," John Andrews, president and CEO of Evans Data, said in a statement. "Consistent with this, the primary motivations for joining a social network are the desire to locate old friends and the need for general communications."

Developers who responded to the survey said that the top three things they look for in social networking sites are the profiles, active community engagement, and quality content. They said that the least important factors are tagging and access from mobile phones.

The survey found that more than 90% of developers check blogs and 70% see blogs as credible sources of information. Developers chose community-moderated forums over sites that are moderated by vendors, with 88% of those responding saying that community moderators are key to social networking sites.

Developers ranked Microsoft first for having the best Web site for programmers, with 27.4% of those polled saying they favored the site. Sun Microsystems ranked second, with 12% of developers saying they preferred Sun's site to others. IBM and Google tied for third place, with less than 10% of developers choosing those sites.

InformationWeek has published an in-depth report on the business uses of social networks. Download the report here (registration required).