As part of Kiva.org's Community Outreach team, I was working on trying to get the "@kiva" account rather than continuing to use our "@kivacs" and "@kivadotorg" accounts. I had contacted Twitter's official support site, one of their investors, and googled the heck out of "how to get your organization's name on Twitter". None of these yielded results, so I contacted the @kiva user directly. After several "@" messages and looking at her tweet frequency I realized she wasn't actively using the service and probably wasn't receiving my messages.
Apparently that got through because very soon after I had a tweet from Kiva (yes, her name was Kiva!) telling me she would be happy to hand over the user name! Great to see that people are willing to help out for such a good cause.
Hopefully this trick can help other nonprofits / orgs/ charities get their names on twitter too. Stalking her friends wasn't immediatly apparent to me!