Update August 26, 2008: I've added at the bottom a comparative image showing the slightly thicker legs of this bird:
This presumed Snowy Egret was photographed at Mitchell Lake Audubon Center, San Antonio, Texas on August 11 2005; obviously the dark gray lores are what caught my eye, but also note that the bill has a slight droop and is more spear-shaped than dagger-shaped - these are supposed to be features that favor Little Egret:
