Let's do a rough revenue calculation assuming $350/Reader and assuming 25964 roughly represents the number Readers...
First year sales revenues of around $350 * 25964 * 12/9 = $12 million.
That doesn't sound bad for a market that people generally feel doesn't exist. And if Connect revenues are doing well, maybe they could have more than $10 million in e-book sales also. (Remember that not everyone is as clever as MR folks, who know all kinds of ways to get content outside of Connect. And even many of us are buying Connect books, especially as related to using the purchase credit.)
Also considering that this is only the first step in trying to create a market, and assuming that it's true that sales are exceeding expectations, one has to think that Sony must be thrilled so far.
Hopefully, they are thrilled enough to invest heavily in future generations of e-Reader devices in hopes of supplying the "Walkman/iPod" of books.