This is an old post, preserved for reference.
The products and services mentioned within are no longer available.
I'm pleased to announce the VIC20 Penultimate Cartridge I have been working on is now going into production by www.thefuturewas8bit.com. Like the nicely cased SD2IEC they produce, the VIC20 Penultimate Cartridge is also going to have a custom case.
UPDATE: I've updated the firmware to V5.0c, and added a user guide and a few more ROMs
UPDATE: Great video review from GadgetUK164
2022 Update: The production version of the Penultimate Cartridge is now available from The Future Was 8 bit