Wizards of the Coast has announced that 1,249 North American stores participated in Magic Game Day, held last Saturday (see 'WotC Plans Magic Game Day').  That represents around 35% of the roughly 3600 stores that participated worldwide.  Based on the 40% of participating stores that have submitted reports to WotC to date, the average number of players per store was 23. 

WotC says its anecdotal reports indicated that new and lapsed players joined current Magic players at the events, stimulating sales of 10th Edition, on which it's already receiving re-orders from retailers and distributors.