We all heard about some Android Trojans are exist out there, they only log the phone calling details and contact numbers, send it through the network to the trojan servers, but recently a new type of Android Trojan show up, it not only log the information, it can record the whole conversation and store it as a .amr file in the SD card, send it to anybody in the dark side. this Android Trojan is discovered by security firm CA.
From now on you should watch the permissions which the Application is asking for, you should think of it carefully, does it really need all those permissions? why a game need to make phone call? why a launcher need microphone control? why a camera app need Internet connection? ask yourself, that is the best defense against many kinds of Android Trojans.