While i'm on karmic atm, haven't had any issues with last track and cdrom offset
I can't rip and encode the last track of any CD.
Assuming you've set the offset to the proper confirmed one for your drive maybe try an 0.6X version.
I have a 0.6b deb attached in post 86 (p. 9), it's about a month old (debs are no longer allowed so won't update), it will install on hardy thru lucid, if so, please read edit
Or if more suitable just grab the latest git
While I haven't used in months maybe I'll try on my hardy install later...
git clone git://github.com/rubyripperdev/rubyripper.git