  We consider a model for the low-luminosity gamma-ray burst GRB 060218 that
plausibly accounts for multiwavelength observations to day 20. The model
components are: (1) a long-lived ($t_j \sim 3000$ s) central engine and
accompanying low-luminosity ($L_j \sim 10^{47}$ erg s$^{-1}$), semirelativistic
($\gamma \sim 10$) jet; (2) a low-mass ($ \sim 10^{-2} M_\odot$) envelope
surrounding the progenitor star; and (3) a modest amount of dust ($A_V \sim
0.1$ mag) in the interstellar environment. Blackbody emission from the
transparency radius in a low-power jet outflow can fit the prompt thermal X-ray
emission, and the nonthermal X-rays and gamma-rays may be produced via Compton
scattering of thermal photons from hot leptons in the jet interior or the
external shocks. The later mildly relativistic phase of this outflow can
produce the radio emission via synchrotron radiation from the forward shock.
Meanwhile, interaction of the associated SN 2006aj with a circumstellar
envelope extending to $\sim10^{13}$ cm can explain the early optical emission.
The X-ray afterglow can be interpreted as a light echo of the prompt emission
from dust at $\sim 30$ pc. Our model is a plausible alternative to that of
Nakar, who recently proposed shock breakout of a jet smothered by an extended
envelope as the source of prompt emission. Both our results and Nakar's suggest
that bursts such as GRB 060218 may originate from unusual progenitors with
extended circumstellar envelopes, and that a jet is necessary to decouple the
prompt emission from the supernova.
