A reader tipped me to the new change to the Sony Style website. (Thanks, Marie!) We are both more than a little baffled as to why Sony would choose to not sell any ereader in the US, but that's Sony for you.
Update: It looks like this story may have been premature. The Sony Reader has been alternating between available and "not available" for a few days now. In my defense, the T2 is not carried by Walmart, Best Buy, or Amazon, so it was safe to conclude that it had been removed from the market.
They have long been telegraphing that they were more interested in selling ebooks on their smartphones and tablets. For example, they released basically the same ereader for 3 years running while at the same time Amazon, Kobo, Pocketbook, Bookeen, and everyone else released new and better ereaders every year.
At this point I think it is safe to say that if Sony weren't selling ebooks on their smartphones they would probably have abandoned the ebook market entirely.