Hi notahacker, I'm Julia from Zidisha. I agree that microloans are more efficient than donations, as they can be recycled over and over as they are repaid and disbursed as new loans, and there is a built-in incentive to invest the funds in something that generates revenue.
I'd go one step further and say that microloans are a great form of philanthropy because they are psychologically healthier for everyone involved. Rather than a charitable handout, they can be structured as a business transaction that benefits both sides. See my post at http://www.huffingtonpost.com/julia-kurnia/about-to-send-a-d... for more thoughts on this.
I'd welcome everyone's opinions / questions about Zidisha.