I have a Positivo Alfa e-reader, which is exactly the 4fff n618 as sold in Brazil. I was researching for information on this reader and found very little information here in Mobile Read (in English, anyway).
I decided to put some things I found about this reader here, as vendors around the world, firmwares, hacks, etc.
So, to start, the vendors that I found and the name of the models:
Brazil
Positivo Alfa
Firmware download (The image viewer and the mp3 player are disabled in this firmware)
Spain
NVSBL L337
Firmware (You have to be registered in this Spanish speaking forum)
Bq Avant (former Booq Avant)
Firmware
Germany
Oyo Reader (A little different, but actually the same hardware)
Italy
Devo EVReader WT
Dutchland
ProMedia E-Book Reader
Firmware
France
Icarus Sense E-Reader
Those are some of the models I found. Other variations include BenQ K60, Pandigital Novel and FNAC Reader.