Not too long ago, Jim Karpen blogged about the Overdrive Media Console. You can find that at the below link.
http://www.iphonelife.com/blog/5/overdrive-media-console-free-app-lets-you-check-out-ebooks-and-audio-books-your-library
I downloaded it myself and have been exploring some of my libraries' offerings when I have time here and there. I'm still trying to figure out general navigation and am finding it a little difficult. I will say though that I have not dedicated a large amount of time to it which is part of my problem.
In my local newspaper today, there was an article from the Associated Press. I thought this would also be of interest.
http://www.berkshireeagle.com/ci_17170928?IADID=Search-www.berkshireeagle.com-www.berkshireeagle.com
