Most nonprofits are struggling to keep just their simple web sites up-to-date and answering the many inquiries they already receive. They don't have the time nor the staff to figure out how to use OSN platforms, nor which ones to use, and also don't have the staff or resources to keep their information up-to-date on these various locations as well their web sites. In addition, "traditional" online communities, whether on YahooGroups or via email, as well as the "old" WWW, are already connecting nonprofit professionals with many more people and organizations than they can keep up with.

Most funders are never going to fund paid staff at a nonprofit to engage in all of these online activities (most funders still balk at paying for things like copy machines or computers). Therefore, the only way most nonprofits are going to be able to use OSN platforms is to find very dedicated, very knowledgeable and very trustworthy volunteers, including online volunteers working from home, school or their own work place, to engage in these activities on the organization's behalf. But, as with any activity, the nonprofit needs to think strategically about engaging in OSN: what's the goal of participation? what will success as a result of participation look like? how will the success of this activity be measured?

I have a lot more thoughts about nonprofits and OSN here:

http://www.coyotecommunications.com/outreach/osn.html

I know that some nonprofit have had success with OSN in raising funds or resources very quickly -- but I think those successes have to be noted with a grain of salt. It's similar to when the web was new and swanky and novel. Eventually, just posting to an OSN that a nonprofit needs such-and-such actually *isn't* going to result in the nonprofit getting such-and-such.