Just played around with iBooks and worked out how to change titles to my heart's content.
In "List" view, touch "Edit", select the book whose title you want to change, touch the title and up pops a keyboard to change the title to whatever you want
I have no idea how this reacts with iTunes syncing etc but it acheives what I want - a fully meaningful list of titles instead of, for example, KALED553BXZ_A or 7814-741352 or wid_manual
Yeah!