BTW, got hold of a Adonit Jot, but it didn't work out - It seems that the touchscreen of the Nook Color is not good enough.
Besides, the problem of a lack of a well thought out interface for annotation, particular on EPUB, remains.
Cheers.
Edit: Found something interestings...
http://www.gizmag.com/atmel-maxstylus/20470/
http://www.atmel.com/microsite/stylus/?source=redirect