In this overnight they could update all Macs to Mountain Lion. It seems that Apple is going to repeat last year as they had announce OS X just a day after announcing there quarterly result and this year same is going to happen as on 24 July Apple is going to announce they Quarterly results.
Mac OS X Mountain Lion will bring over 200 changes like better integration of OS X with iOS, Dictations, iCloud, better integration of Facebook and Twitter and so on. Apple has already announced that Mountain Lion will be available on July. Users can get OS X Mountain Lion from Mac App Store for $19.99 on the day of launch