I recently emailed audible.com asking if they will be supporting the 8100. Looks like they have a program in beta. So if you're interested in downloading subscription audio books you might be interested in their response:

As per your email, I understand that you are wondering on whether or not your Blackberry 8100 is compatible with Audible. And actually, over the past few weeks, we have just launched and created some Beta software for Java-Based Mobile devices like the Blackberry 8100 . So, if you click and look through the following links, you will be able to find out how to install and use the Audible Air program on your PDA:

Title: Manually Installing Java AudibleAir
URL: Answer

Title: Java Audible Air Guide
URL: Answer

Also, please try going through our software page (www.audible.com/software), as under the "AudibleAir Beta for Java Phones" section, it will give you instructions as well. If you have any questions, since this still under Beta Testing, you will have to contact "betaprogram@audible.com" if you do run intro any trouble with the software.

That is great news! I installed the app on my Pearl last Friday, but for some reason I got the error "invalid account details" each time I tried to activate the device. I have been working with Audible support, and will post the fix for this when I get it.

I've installed AudibleAir on my T-Mobile Pearl, I've gotten past the account login without trouble, and I've pulled down info on my library. When I try to download a program, though, I'm stuck in a "Connecting" mode that never times out and never moves the ball forward either.

Any ideas?