Some hands-on prototype demos from COSCUP 2010 conf in Taipei:
http://www.youtube.com/watch?v=8KXFWF_4drk
Looks decent, but early stage still.
I'm really waiting for a large-format epub reader with a decent PDF-support (hopefully color, but that's a bonus). Looks like 2011 *might* offer this, if we are lucky.