I think Jeff isn't giving out sales figures to continue to protect his pet project.
Sales are probably modest but investors don't want modest sales, they want the massive sales like the iPhone out of the gate.
Like a Hollywood blockbuster. The film may be great, touching audiences and critics alike, but it came out right after "Iron Man" that did a bazillion dollars it's opening weekend. That little film might take a while for others to discover it, but it doesn't mean it's bad film or doesn't deserve to continue to find its audience.
My guess is the same with the Kindle, hence his silence so investors (and pundits) don't squawk.
Can you imagine the outcry of bloggers if even Amazon couldn't do a succesful e-reader?!?
We'd all be subjected to yet another litany of e-books are dead, long live paper books, only socially challenged nerds in their mother's basement read e-books.
Sheesh!