Given the fact that a launch of this stature is paramount for Sprint, it's understandable that the company would want to modify their hours to work around the launch. According to the leak, Sprint retail stores will close at 4 PM, while employees stay and put up Pre displays and decorations. On Saturday, the stores will open bright and early at 8 AM and start dishing out Palm Pre's at $199.99 after a $100 mail-in rebate.
The real question is whether you'll have time to stop, grab breakfast, and mosey over to the Sprint store to purchase one, or if the lines will be backed around the corner like the iPhone launch. Time will tell, and June 6th isn't too far away.