  Use of the highly sensitive Hokupa'a/Gemini curvature wavefront sensor has
allowed direct adaptive optics (AO) guiding on very low mass (VLM) stars with
SpT=M8.0-L0.5. A survey of 39 such objects detected 9 VLM binaries. Most of
these systems are tight (separation <5 AU) and have similar masses (Delta
Ks<0.8 mag; 0.85<q<1.0). We find a sensitivity corrected binary fraction in the
range 15+/-7% for M8.0-L0.5 stars with separations >2.6 AU. This is slightly
less than the 32+/-9% measured for more massive M0-M4 dwarfs over the same
separation range (Fischer & Marcy 1992). It appears M8.0-L0.5 binaries (as well
as L and T dwarf binaries) have a much smaller semi-major axis distribution
peak (~4 AU) than early M binaries. We also find no VLM binary systems (defined
here as systems with M_tot<0.185 solar masses) with separations >15 AU.
  We briefly explore possible reasons why VLM binaries are slightly less
common, nearly equal mass, and much more tightly bound compared to more massive
binaries. We find that a kick during the ejection of a forming VLM binary from
a close triple or quadruple encounter (imparting a differential kick of ~3 km/s
between the members of the binary) could reproduce the observed cut-off in the
semi-major axis distribution at ~20 AU. However, the estimated binarity (~<5%;
Bate et al. 2002) produced by such "ejection scenarios" is below the 9-15%
observed. Similarly, the dynamical decay models of Sterzik & Durisen (1998);
Durisen, Sterzik, & Pickett (2001) also cannot produce a VLM binary fraction
above ~5%. Our estimate of a fragmentation-produced VLM binary semi-major axis
distribution contains a significant fraction of ``wide'' VLM binaries with a>20
AU in contrast to observation. Hence more detailed theoretical work will be
needed to explain this very interesting VLM binary population.
