bill - 1:43 am on Jun 7, 2013 (gmt 0)
I'll change my answer a bit as this has been split off from another thread...
HootSuite is probably the best way to manage multiple users of SNS accounts these days. I wish there were other good alternatives. I really don't care for HootSuite, but I'm forced to use it.
It's web based and works in a browser. If you're working with other people you can keep the master key, and the other people accessing the account only need to be granted access through HootSuite. From the outside nobody can tell that multiple people are working the accounts.
One of the best features is that in addition to being able to control Twitter, Facebook, LinkedIn, Foursquare, MySpace, WordPress and Mixi accounts, is that you can also post to Google+ Pages. They're one of the few companies that can post to Google+. Unfortnately the API for Google+ is sketchy and often fails, so you really have to keep an eye on that.