iOS 6 for the iPhone, iPad and iPod touch is scheduled for release today, but Apple hasn't said exactly when to expect the update to roll out. Based on previous releases, however, it's not too hard to guess when it might go live: 1PM Eastern time.
Gamel Sabry from Absinthe Jailbreak logged previous release times from Apple and put together a chart showing by city when we can expect to see iOS 6 come out.
Absinthe Jailbreak's table estimates iOS 6 release times by city
Based on historical data, his times seem reasonable. Since Apple hasn't said exactly what time of day the update will hit, however, we could be only minutes, or several hours, away from the release.
iOS 6 will be available as a free over-the-air update for the iPhone, iPad and iPod touch.