There has been a lot of hype building up around Just Cause recently;
"JustCauseIt is a social network with a philanthropic twist. Like Idealist, JustCauseIt lets you connect with other users who are troubled by the current state of the world and wish to spearhead positive changes for society."
"When the folks at JUSTCAUSE came to us with their idea and told me their mission is... I knew that this project was a good fit for us."
KillerStartups also found this great blurb which I somehow managed to miss:
“JustCauseIt.com (beta) is a social networking site connecting people to causes to create change. It’s social networking as you know and love it, but it actually has a purpose”