  The plethora of asymmetric planetary nebulae and the curiously high momenta
of pre-planetary nebula outflows suggest that rotational energy is extracted
from the engines. Magneto-rotational outflows driven by dynamos might be
operating therein. I summarize scenarios involving (a) an isolated AGB star and
(b) a binary. The efficacy of (a) requires re-establishing differential
rotation over the AGB star's lifetime, whereas (b) delivers the angular
momentum at the end of the AGB phase when needed, and may involve turbulent
disks. Both can produce fields that drive outflows of the required mechanical
luminosity and momentum, though weak points and open questions require further
study.
