An article in the Financial Times ("Why Sony Lost the Battle of the E-Book") suggests that, despite the Sony Reader's earlier market presence, the unique features of the Kindle (e.g., wireless access to e-books), its large e-book stock (145,000 titles), and its strong unit sales (240,000 units) and e-book sales (12% of Amazon book sales in both digital and print formats) bodes ill for the Reader's ability to attain marketplace dominance.
Read more about it at "Amazon May Have Actually Sold a Bunch Of Kindles (AMZN)" and "We Know How Many Kindles Amazon Has Sold: 240,000."
One correction:
“(12% of all Amazon book sales) ”
should be
“12% of Amazon sales for those books available in Kindle form”
Which is a very different and considerably smaller number.
I didn’t think the Sony Reader ever had market dominance or even much of a market presence, so it’s not a real difficult race to win.