Here's what i've got so far.
I've posted it up as a contribution: http://www.ubercart.org/contrib/2650

As I mention on the contribution page, I have only been able to test against eWay's test server, not the live one - as I don't have access to a valid account yet.

Successful payment invokes the w-ng event "eway_payment_processed", so you can use that in custom workflows if you like. It then uses the existing action from the Order module "uc_order_action_update_status", to update the status of the order.

It doesn't yet check to see that the order balance is actually 0, as I have yet to figure that out via w-ng. This means that if you have "process payments at checkout" turned on, a partial payment will mark the status as payment received anyway.

I've also added the localisation template, not that anyone's likely to need it - but it's an easier way of making customisations to the text than hacking the .module file.

Anyone else had a chance to test it yet? I haven't had any feedback on it yet.

Cheers,

Daniel