I've been on a couple of international fights recently (777 and A330) where engine start up has been initiated while we are still at the gate before pushback. Is this something new? I always use to recall being pushed back by the tug and then gradually the engines would be started (the occasional DC9 reverse thrust push back excepted).
I noticed this most recently at both JFK and DXB. Does the distance of the aircraft from the actual terminal have anything to do in determining this?