The original firmware also supports resuming from the last played position in podcasts and audiobooks. Whenever you select a partially listened item, you get a prompt to continue from the last point or start from the beginning. It's really handy and honestly I couldn't live without it.

There's a simple binary database in the root folder that keeps this information, but it gets reset whenever you add/remove files. Now that I think about it, it might even be possible to backup that info and restore it afterwards, although I never really needed to do that. I don't usually have more than a couple books/podcasts in progress, so it's easy to remember where I left off, if needed.