But it's only available in Japan.
Sony announced earlier today that they were releasing a new firmware for the local Japanese edition of the Sony Readers. They added support for the "dot Book" (.book) format, which (according to the press release) is a comics friendly format.
This is actually the second format that Sony support in japan but not in the USA. The Japanese firmware for the Touch Edition and Pocket Edition also support the XMDF format (in addition to Epub and PDF). You might have heard of it in relation to the Sharp Galapagos ebook readers, which were but never seemed to have hit the market.
Starting tomorrow Sony will also be selling ebooks in the new format.