  The fact that both the D6-brane and the orientifold 6-plane have smooth,
horizon-free descriptions in M-theory makes them especially useful in
understanding certain aspects of brane physics. We briefly review how this
connection has been used to understand a number of effects, several of which
are associated with the Hanany-Witten transition. One particular outcome is a
"confinement mod 2" effect for zero-branes in the background of a single
D8-brane. We also discuss an interesting puzzle associated with flux-expulsion
from D6-branes in this context. Finally, we discuss the promise of using a
similar M-theoretic description of the orientifold 6-plane to understand the
consistency of stringy negative energy objects with the 2nd law of black hole
thermodynamics.
