I don't have a Radio Userland or Manila account, so I haven't been able to test BookPost with those tools. I know it works with Blogger and Movable Type. If you happen to try it out with Radio or Manila, let me know how it works for you. I've found the implementations of the Blogger API are all different. I tried to keep my code as generic as possible so it would work with them even with the differences, but you never know until you test it out.