Pretty much..  I had a transfer case on a 4Runner let go at about 60
mph.  No, I wasn't in 4WD and the front hubs weren't locked.  Output
bearing failed, turned red-hot, melted and then seized.  Peeled the
back of the xfer case off, dropping the front yoke of the driveshaft
onto the pavement.  

The rear of the truck jumped (according to the guy driving behind me)
about 4' in the air and the driveshaft disintegrated and flung chunks
of metal all over the place.  Biggest piece I found was the front yoke
and about 3" of shaft twisted into a cone off the back of that.

Transfer case oil caught fire and luckily I had a water bottle with me
to put it out.  Destroyed the ring gear in the rear diff as well.

Since you say you lock your hubs I'm assuming they are manual.  I back up a
little even with manual hubs to make sure they are disengaged.  When I first
installed them and rotated the wheels it felt like they were still engaged
after unlocking them until I rotated the wheel about 2/3s of a turn.

That or busted driveshafts & U-joints. Part time 4wd is not intended for
street use.