I'd like to know as well. The closest I've found is the eBook compatible Mobipocket reader that supposedly will allow you to download an entire cache's description and log page, then read it on the BB screen just like you would with a desktop browser. However, after downloading the sample "caches I have not found" page, I couldn't figure out how to create and download my own list of caches I want to go searching for.
The only place I can find that Groundspeak talks about this capability is on the Premium Member page at: http://www.geocaching.com/subscribe/
I don't think there is a RIM geocaching software equivalent to the tools that are commonly available on Palm PDA's. I've looked on RIM's third-party software site and haven't seen anything at all.