The next iPhone's unveiling date is safely locked down. Whether or not it arrives at every US carrier simultaneously is up in the air, however, and there's signs that Sprint's model might not ship as quickly as we'd like. Carrier training documents obtained by iSource, which we've since verified are real, would require that sales staff and technicians all be ready to offer "in-store Apple support" on October 15th, wrapping up their earliest training by the 30th
