Thanks for the follow up. Please keep us posted.
As I expected, the SunTrust SkyMiles debit card counted as a purchase and I have an additional 41K miles in my account for the low, low price of just $3.89:
04 May 2010 Non Air Activity SunTrust SkyMiles Platinum Card - Purchases (posted on 04May2010) 41018 0 41018
Why anyone would use a credit card to pay taxes and earn miles when a debit card is so much cheaper is beyond me.