I have used Overdrive for a while on my iPhone 3g without any problems. I have swopped to an Adroid phone, Sony Ericcson Xperia Ray (running Gingerbread) and, although I can download the app through Marketplace with no problems, I can't get my phone authorised by Adobe despite using the correct sign in.
Digital Editions does not support iPhones. Check the list of supported
devices in the Digital Editions Help function.