Tech guru John C. Dvorak has it on good authority – a sales rep from Cingular – that the Apple iPhone’s battery goes dead after only 40 minutes of talk. Because of the info, it is Dvorak’s recommendation that Apple should simply pull the plug on the already announced and already FCC-approved iPhone. The recommendation can be read in full in Dvorak’s podcast. There’s more. According the Cingular rep, the iPhone has other issues, including the interface “fouling up constantly.”