We demonstrate reconfigurable demultiplexing of arbitrary single or multiple 10 Gb/s tributary channels from a higher rate 40 Gb/s data signal using a programmable planar lightwave circuit (PLC) and four-wave mixing (FWM). The PLC is a thermally tunable six-stage lattice-form Mach-Zehnder interferometer fabricated in silica-on-silicon. We present results for optical time-division-multiplexing (OTDM) demultiplexing of both return-to-zero on-off keying (RZ-OOK) and differential phase-shift-keying (RZ-DPSK) data.