So far...

iBooks 2 - a lot richer content with videos, images, chapters, integrated KeyNote files etc...
iBooks Author - easily create and publish eBooks for iBooks 2 (free and available now).

Now on to iTunes U.

This is something I use so could be interesting.

iBooks 2 is not apparently any different to iBooks 1, guess most of the changes are in the background
The 'free' textbook you can download (think Life on Earth done by Americans) is quite impressive
iBooks Author only works on Lion. The templates are... interesting. Feels more like Keynote than Pages. quite a useful set of default 'widgets', I'd imagine there will possibly be a market in third party ones if it's 'pluginable'.

iTunes U is basically the section from iTunes mac/windows as an iOS app with an iBooks lite interface.. Will still be quite useful. Think a lot of higher ed places will still like to do their own thing though.