  Type I string theory in the presence of internal magnetic fields provides a
concrete realization of split supersymmetry. To lowest order, gauginos are
massless while squarks and sleptons are superheavy. For weak magnetic fields,
the correct Standard Model spectrum guarantees gauge coupling unification with
\sin^2{\theta_W}=3/8 at the compactification scale of M_{\rm GUT}\simeq 2
\times 10^{16} GeV. I discuss mechanisms for generating gaugino and higgsino
masses at the TeV scale, as well as generalizations to models with split
extended supersymmetry in the gauge sector.
