We study the Sivers effect in transverse single spin asymmetries (SSA) for
pion and kaon production in Semi-Inclusive Deep Inelastic Scattering (SIDIS)
processes. We perform a fit of A^{sin(phi_h-phi_S)}_UT taking into account the
recent data from HERMES and COMPASS Collaborations, which allow a new
determination of the Sivers distribution functions for quark and anti-quark
with u, d and also s flavours. Estimates for forthcoming SIDIS experiments at
COMPASS and JLab are given.Comment: 4 pages, 1 figure. To appear in the proceedings of the XVI
International Workshop on Deep-Inelastic Scattering and Related Subjects, DIS
2008, London, U.K., 7-11 April 200