Read the article: apparently the good news is that the "Send to Kindle" tools are announced to support .epub file extensions directly soon. The article makes the assumption that "Send to Kindle" will be reformatting .epub files to Kindle native formats and uses that assumption as the basis to rant about the Kindle native formats, but anecdata (such as the USB support and file rename workaround) again suggest kindles already support ePub well enough and that assumption may not be valid and "Send to Kindle" may not wind up reformatting ePub files (much).