Use your mobile web browser (BlackBerry, Windows Mobile, Android, etc. -- even iPhone, though there is an iPhone specific app) and visit http://library.logos.com.
You should have access to some basic books; if you sign in you should get more, and if you sign in and are a Logos 4 user, many of your book should be available through the mobile device.
This is still in beta, and we're working to improve it, but we'd love to get your feedback. We're starting with basic functionality, and then adding more interactive features as we go (and as the device browsers allow).
Enjoy!
-- Bob