Well it turns out that someone with Maryland license plate number 46A (the same as Rice's legislative plate number) was issued a DC parking ticket on that day, in the same area where the NowPublic photo was taken, and as of November 29th, 2009 that citation for $60 was still unpaid.
It is unclear why this citation went unpaid. However we do know that Maryland Lawmakers can receive special legislative license plates for which the state of Maryland pays the fees. We also found many other 'low numbered' license plates in the DC parking ticket database, some dating back 9 or 10 years, so it's possible that DC has a hard time enforcing tickets against plates registered to state governments. However since Delegate Rice voted in favor of Senate Bill 277 authorizing statewide speed cameras in Maryland, we assume he is OK with the idea of being hounded by cameras all time time and being presumed guilty. So we suggest that he 'just pay the fine' as local govt officials in Maryland are keen on telling citizens to do.