HarryT is right that the Mobipocket implementation on the iRex iLiad is extremely weak. Not only is it missing bookmarking, it's also missing searching: there is no way to search for text in a Mobipocket document. And the pen-annotation stuff does NOT work with Mobipocket ebooks on the iRex; that functionality is available only when reading PDFs.
===
ROBERT J. SAWYER, Science Fiction Writer
*** Hugo Award winner for HOMINIDS ***
http://sfwriter.com *
sawyer@sfwriter.com