I think Mutual Credit module http://drupal.org/project/mutual_credit have strong sinergies with UC Store Credit.
It's basically a mutual credit engine for virtual currencies with a different range of applications, and with complete views integrations, 3rd party payment systems, statistics and so on.

They just released last week their 6.x-2.0 version and seem to have an experimental Ubercart payment method.
It could be a good oportunity to join efforts.