Hey, that's a great question. DCF is actually based on Ning so a DCF app would really be a Ning app. The Ning developers have chosen to create a mobile version of their web interface, rather than a custom iPhone application. This means if you visit DCF on your iPhone, you'll automatically be shown the iPhone-enhanced version of the DCF interface.
If you're curious what that interface looks like, you can check it out from your PC using the following URL:
I just discovered that app on my iTouch yesterday. I was playing around with it and I have to say that it kind of sucks. there's no way to access the featured blog posts unless they've been "active" recently. so if I'm away from my computer and haven't had a chance to check the fix in a couple of days and I'm interested in what's been on the main page, I'm out of luck. well, I guess I could click on "view regular version" but that sort of defeats the purpose. I sure wish they'd work on the design a little.