Probably if you are used to A200/300/350/700/850/900, then you might be not used to it since the control dial is next to shutter release.
But for current Alpha bodies, the control dial is lower, so it's not easy to mistook it.
I agree, I've never held any of the above mentioned DSLR before... After the first week of 'fumbling' and 'feeling' the whole body, I've not accidentally switched off the camera while using the control dial since.
But I admit, I've accidentally triggered the shutter release on the vertical grip while 'gropping' the camera ie: when mounting on monopod, etc.:bsmilie: