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.
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.