As surgery centers that bill electronically anxiously await for upgrades that will make their billing programs compatible with Medicare payment changes, software vendors prepare as best they can and ask their customers for patience. Medicare is expected to issue its final 2008 ASC payment rates this month, giving vendors precious little time to upgrade their products by the time the new payment system takes effect Jan. 1. Not quite the Y2K scare, but potentially a logistical nightmare if scores of centers can't code and bill correctly a few weeks from now.