  We investigate the role of the compact object in the production of jets from
neutron star X-ray binaries. The goal is to quantify the effect of the neutron
star spin, if any, in powering the jet. We compile all the available measures
or estimates of the neutron star spin frequency in jet-detected neutron star
X-ray binaries. We use as an estimate of the ranking jet power for each source,
the normalisation of the power law which fits the X-ray/radio and
X-ray/infrared luminosity correlations L_(radio/IR) proportional to
L_(X)^(Gamma) (using infrared data for which there is evidence for jet
emission). We find a possible relation between spin frequency and jet power
(Spearman rank 97%), when fitting the X-ray/radio luminosity correlation using
a power law with slope 1.4; Gamma=1.4 is observed in 4U 1728-34 and is
predicted for a radiatively efficient disc and a total jet power proportional
to the mass accretion rate. If we use a slope of 0.6, as observed in Aql X-1,
no significant relation is found. An indication for a similar positive
correlation is also found for accreting millisecond X-ray pulsars (Spearman
rank 92%), if we fit the X-ray/infrared luminosity correlation using a power
law with slope 1.4. While our use of the normalisation of the luminosity
correlations as a measure of the ranking jet power is subject to large
uncertainties, no better proxy for the jet power is available. However, we urge
caution in over-interpreting the spin-jet power correlations, particularly
given the strong dependence of our result on the (highly uncertain) assumed
power law index of the luminosity correlations. We discuss the results in the
framework of current models for jet formation in black holes and young stellar
objects and speculate on possible different jet production mechanisms for
neutron stars depending on the accretion mode.
