My hacked version is here:
http://drop.io/jetbookHackADE The file is jetBook_v35a2.zip
Firmware Version 35a allows you to not have to strip DRM from your ADOBE DRM'd Epubs to read them on your jetBook. Remember you need to authorize your jetbook with Adobe Digital Editions on your PC before you can read DRM'd epubs. And with my hacked version, you can modify the stylesheet to make changes to how the EPUBs (DRM'd and not) are displayed.
Note that I only changed the following bytes of the adobe mobile reader with a hex editor:
res:///adobe/pxf/userStyle.css
to
res:///mnt/flash/userStyle.css
Then I created userStyle.css in the top directory of the jetbook internal memory. I also created a fonts directory in the top directory of the jetbooks internal memory and added the fonts referenced in my stylesheet. If you want to try changing fonts, line spacing, margins, etc... first try my version as is to see how it works... then I would suggest not changing too much at one time in userStyle.css. Cascading stylesheets are really not my field but I managed to get things pretty much looking the way I want them to.