Late night talk show host David Letterman gave Apple and its iPhone 4 issues the special treatment on Tuesday night. Letterman said the “Top 10 signs you’ve purchased a bad iPhone” are: To make a call, you have to insert a quarter into the phone. Apple is planning a press conference on Friday and will have updated iOS software for its phones this week. The iPhone 4 debacle isn’t the first fodder Apple has given TV personalities to use in their shticks. Ellen Degeneres aired a fake commercial mocking the iPhone’s ease of use.”]