It seems that, probably due to the rush to get the device in stores and it being re-branded, the reader when connected to USB has no vendor or product identifier:
(‘USBSTORDISK&VEN_&PROD_&REV_JZ4740_PAVO&0′, 1, u’G:’)
This may well be why the device doesn’t show as a removable storage device on mac and linux.
If we can get Elonex to fix this then maybe it will work on all platforms, having no identifier also means that the author of Calibre can not currently write a driver for the reader to work with his software.
I’ll contact Elonex regarding this issue, hopefully they can get a fix into the firmware.