Apple Stores usually only begin their training of new software in the couple of weeks leading up to a respective product launch (obviously this time around could be different, though). Apple beginning their iOS 5 training within the last few days could mean a launch sooner than the recently rumored dates of mid-to-late October.
In addition to store employee training, carriers are also getting special versions of iOS 5 software.
Separately, Apple’s most prominent carrier partners have been seeded near-final builds of iOS 5 for final testing. This build is newer than the betas seeded to developers and includes some unique features. According to a source testing this build, FaceTime over 3G is active. According to this source, testers are being instructed that 3G FaceTime testing is a high priority.
Their versions also reportedly running Apple's new Nuance-powered speech-to-text feature, though NOT the full on SIRI-powered Assistant feature that's also been rumored for iOS 5.
Apple could still be working on it, could have shelved it, or could be keeping it exclusively for new iPhone 5