Steve Litchfield has published an article today on getting the N93 version of Mobireader working on the N97.
http://www.allaboutsymbian.com/features/item/Mobipocket_and_Ebooks_on_the_Nokia_N97.php
While it can open and read books it still lacks the nice features (like autoscroll) which I dearly loved on my Nokia 9300.
UPDATE****
Another IMPORTANT feature which doesn't work here is HYPERLINKS. There is no way to select them to be able to follow them.
The Autoscroll feature, while selectable from the menu, just causes a lot of pixel activity at the bottom of the screen for a period of time, then changes the page--and not necessarily after you've finished reading it!
Also...the only way to turn a page is with the keyboard open using the Navigation button/space key/enter key in landscape mode.
We really, really need a good ebook reader for the N97!