Yes, this is true...
The MD's I've spoken to about this mentioned that ever since the 80 hr/week rule went into effect for the residents (who used to work crazy hours and more than that, obviously), someone has to pick up the slack, right? It certainly won't be the attendings and if it's not the residents, then it would fall upon the 3rd/4th year med students to work more than 80 hours per week if need be. They wouldn't be working over 80 hrs/wk for a few months straight or anything, but there will be periods like that and then other periods in which they work significantly less, so that the total number (and consequently the average number) would still be pretty balanced.
But just remember, the med students will be the ones picking up the slack when it's all said and done.