iPhone OS 4.0 software was just announced this month, but a lot of iPhone and iPod touch owners are excited about it. Just when is the iPhone 4.0 release date? Apple only said summer 2010, but we can expect the iPhone OS 4.0 firmware to be released during June because that's the same month Apple released the iPhone OS 3.0 online update last year. The iPhone 4.0 update is a really big update and adds more than 100 features to the iPhone, including multi-tasking and categorizing of apps.