  Sgr A* is a compact radio source at the Galactic Center, thought to be the
radiative manifestation of a $2.6\times 10^6 M_\odot$ supermassive black hole.
At least a portion of its spectrum--notably the mm/sub-mm ``bump''--appears to
be produced within the inner portion ($r< 10 r_S$) of a hot, magnetized
Keplerian flow, whose characteristics are also consistent with the $\sim 10%$
linear polarization detected from this source at mm wavelengths. (The
Schwarzschild radius, $r_S$, for an object of this mass $M$ is $2GM/c^2\approx
7.7\times 10^{11}$ cm, or roughly 1/20 A.U.) The recent detection of a 106-day
cycle in Sgr A*'s radio variability adds significant intrigue to this picture,
since it may signal a precession of the disk induced by the spin $a$ of the
black hole. The dynamical time scale near the marginally stable orbit around an
object with this mass is $\approx 20$ mins. Thus, since the physical conditions
associated with the disk around Sgr A* imply rigid-body rotation, a precession
period of 106 days may be indicative of a small black hole spin if the
circularized flow is confined to a region $\sim 30 r_S$, for which $a\approx
(M/10) (r_o/30 r_S)^{5/2}$. The precession of a larger structure would require
a bigger black hole spin. We note that a small value of $a/M$ ($< 0.1$) would
be favored if the non-thermal ($\sim 1-20$ cm) portion of Sgr A*'s spectrum is
powered with energy extracted via a Blandford-Znajek type of process, for which
the observed luminosity would correspond to an outer disk radius $r_o\sim 30
r_S$. Such a small disk size is also suggested by earlier hydrodynamical
simulations, and is implied by Sgr A*'s spectral and polarimetric
characteristics.
