Only it's not. Sony dropped a few hints about ereader sales at the Electronic Book Summit in Tokyo yesterday. According to Tech-On:
The most selling model is the "Reader Touch Edition," which is equipped with a 6-inch electronic paper (e-paper) device. Though Sony did not disclose a specific sales volume, it said, "The Touch Edition has almost been sold out, and we are sorry for causing inconvenience to appointed stores."
On the other hand, Sony said that there is enough stock of the "Reader Pocket Edition," which features a 5-inch e-paper device.
I hate "news" reports like this. It's meaningless. How many did they ship? Dozens? Hundreds? Thousands? We don't know.