I must add the another vote for the annotation feature!
however a very simple market analysis will reveal that there is an important niche made of academics but also of other professional who dedicate most of their time to read and additionally travel!
so, if PB manage to satisfy (before others) some basic requirements of this niche they can make a fortune!
1° these persons want a comfortable device for reading A4 file size (this is a good point of 900 series)
2° the same persons want to manually annotate their papers, reports or prospectus, save their annotation and print them! (everybody on this forum seems to agree that there is no trace of such thing on the PB device)
3° these persons are working mostly with doc and pdf files. so the reader should be able to process very quickly these formats. (in its actual state PB903 may need years to open some .pdf file!)
4° eventually, the same persons may want to have and to manage an agenda (not just to look at a plain calendar!) synchronized with their own agenda on their pc and/or their webphone.
commercially speaking, it will be an error to try to satisfy all types of consumers instead of focusing on a particular segment of consumers (irex is already a classical example that is now taught in business schools!) and, in my eyes, it will be an error to ignore professionals who may consider the ereader as an investment capable to ameliorate their productivity. PB should seduce them with the above arguments before they buy an ipad!