Greetings,
It's been a long time, but ShipSync has finally received a much needed update! This new version requires Magento 1.8 or newer, since there were a number of structural changes to the Magento code that prevented backwards compatibility.
https://github.com/five23/shipsync-community
This build is hot off the presses so there will most certainly be a few bugs, but it should be far more stable than the last version. Countless fixes have been implemented, but there's still a long way to go before this thing is in ship shape (pardon the pun), so please log any issues on Github and I'll do my best to take care of them quickly.
Most honor,
David