It just depends on the cranks. The "latest, greatest" stuff mostly uses outboard bearings, but there are plenty of cranks out there that use bearings inside the bb shell. But even then, you've got ISIS (10 splines), Octalink (Shimano 8 spline, V1 or V2), and of course square taper spindle/crank interfaces. Again, it just depends on the specific crankset you decide to go with.