Yeah, depends on smoke chamber temp, meat cross-sectional density, etc, but I've had stalls anywhere from lower 140's to mid 160's. Come to think of it, I've had stalls in the 180-190* range, but those were probably forced stalls due smoke chamber temp variations. A true stall/plateau is caused from water evaporation inside the meat as part of the normal cooking process. Water vapor cools it's environment, hence the internal meat temperature climb rate falling off, stopping, and in some cases falling. I've seen internal temps drop by almost 10* with no indication of a drop in chamber temps.
The main thing to remember with stalls is to be patient...it will snap out of it on it's own, but only when it's good and ready.
Eric