  The major multi-epoch VLBA programs are described and discussed in terms of
relativistic beaming models. Broadly speaking the observed kinematics are
consistent with models having a parent population which is only mildly
relativistic but with Lorentz factors extending up to about 30. While the
collimation and acceleration appears to mainly occur close to the central
engine, there is evidence of accelerations up to 1 kpc downstream. Generally
the motion appears to be linear, but in some sources the motion follows a
curved trajectory. In other sources, successive features appear to be ejected
in different directions possibly the result of a precessing nozzle.
  The launch of GLAST in 2008 will offer new opportunities to study the
relation between radio and gamma-ray activity, and possibly to locate the
source of the gamma-ray emission. VSOP-2 will give enhanced resolution and will
facilitate the study of the two-dimensional structure of relativistic jets,
while RadioAstron will provide unprecedented resolution to study the fine scale
structure of the jet base.
