Verizon Wireless has informed employees of an upcoming vacation blackout, suggesting that the next-generation iPhone will launch during that time. Citing a “trusted Verizon employee”, TechCrunch reports that Verizon has called for a staff-wide vacation blackout from Friday, September 21 to Friday, September 30. Apple is expected to announce its next-generation handset on September 12, and there has traditionally been a delay of slightly…