Apple Stores are rumored to have an overnight shift on July 24. This could mean Apple will release OS X Snow Leopard on July 25.
Apple has already said to release OS X Snow Leopard in July. The exact date has neet been revealed. The OS X Snow Leopard Golden Master got released to developers last week. This means Apple is ready with OS X Snow Leopard. A new rumor report on 9to5Mac says that Apple Store employees have to work an over night shift on July 24. These shifts are for changing of store displays.
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On top of that Apple is releasing the Q3 2012 earnings are announced on July 24. The OS X Lion launch also was one day after an earnings call.
Of course this could also mean nothing, but from where I stand it sounds likely.