Nope, I have full android (jellybean) and that stores EVERYTHING the apps produces on command. It can store the app along with the associated data.
Yeah but this requires root, and a root user would know the risks of producing such backups. What app are you talking about right now?
Also, there are many ways that someone could have gone on his phone and posted something, who said anythng about a public place? Maybe it was a friend or someone living in his house just posting something random when they got bored?
What kind of "friend" would go to your phone, and start using it? Also i doubt that he had his screen on without a screen lock. Also it does not really matter, since i think that the point of this thread was to discuss technical details rather than discussing people who could possibly access the phone.
By "hacking" I mean more a a brute force attempt, there are parts of the phone that can be taken over from the web client of play.google.com. If these were ammended by a little programming then a pasword for a bitcointalk account can be gathered, obviously this is unlikely as they'd change the email address and password after logging in.
You cannot bruteforce a google account, because after few invalid tries it does ask you for captcha, so that makes no sense. Would you care to actually define the technical details of the attack you are meaning, and there are no any tools that actually can solve recaptchas as far as i know.