As noted by others, there is a lot of currency risk and other legal issues which makes Bitcoin a difficult proposition for Kiva.
For those worried about interest rates, I understand why you might initially find some of the high interest rates to be appalling at first glance, but a simple explanation should help you understand why they are that way in some places.
Let's take an imaginary field partner and say they are offering loans at 50% APR to borrowers in a rural village in Mexico. The average loan size is $400.
The administrative cost of setting up the loan can be significant, all the time for initial loan applications, putting people into the MIS, setting up repayment schedules, etc. Let's say that cost $75. Then, there is the cost to collect the loan repayments. Remember, we are talking about a remote village, somewhere that takes a 3 hour motorcycle ride to get to from a major city. This 3 hour ride to collect on loans happens every 2 weeks for 6-12 months. Thus, you have the loan maintenance cost, let's say $100. Finally, you get down to the actual rate the microfinance institution is charging just to stay afloat (if you look at the return our partners are getting, for the vast majority it's just enough to stay afloat), and say that interest is around $25. So $75 + $100 + $25 = $200 plus the original loan $200 + $400 = $600 and thus you have the 50% APR.
Compare this to the only alternative available in that area, a back alley loan from a loan shark for 250% APR, compounded daily. The loan shark has low overhead so it's mostly just cash in their pockets, unlike most of the MFI's who use their proceeds to expand loan offerings or offer other care (like health information) along with the loans they are giving out.
Anyways, I could still see how some people would see that as excessive, despite how the APR jives with the cost, in that case one could just choose not to lend through Kiva or to only loan to borrowers who go through an MFI with a low interest rate. Personally, from the lenders I've talked to and borrowers I've heard from, they are happy with what is being offered to them. It's worth noting that none of this money goes to Kiva. We run off of donations, corporate grants, etc. There are of course, as mentioned, many other organizations now which lend as well and one could check them out. Paypal's offering (microplace I think it's called?) actually returns interest to lenders if you are in to that.
Alternatively, Kiva just launched a direct peer-to-peer lending system called Kiva Zip,
https://zip.kiva.org/, however you'll have to wait a bit because it's still in beta, it's been really neat to participate in it so far.
I'd be happy to answer any questions about Kiva if anyone has any, or you can check a page I actually made for the website:
http://www.kiva.org/about/how Personally, I think we are doing amazing things, but my opinion is naturally skewed cause I work here and think it's the best job ever
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