Observation of B-->K0Sπ+π- and Evidence for B-->K*+/-π-/+

We report on a search for charmless hadronic B decays to the three-body final states K⁰_Sh⁺π^-, K⁺h^-π⁰, K⁰_Sh⁺π⁰ (h^+/- denotes a charged pion or kaon), and their charge conjugates, using 13.5 fb^-1 of integrated luminosity produced near (s)=10.6 GeV, and collected with the CLEO detector. We observe the decay B-->K⁰π⁺π^- with a branching fraction (50⁺¹⁰_-9(stat.)+/-7(syst.))×10^{- 6} and the decay B-->K^*+(892)π^- with a branching fraction (16⁺⁶_-5(stat.)+/-2(syst.))×10^{- 6}.