We report the fabrication and experimental verification of a multiwavelength high-speed 2 x 2 silicon photonic switch for ultrahigh-bandwidth message routing in optical on-chip networks. The structure employs only two microring resonators in order to implement the bar and cross states of the switch. These states are toggled using an optical pump at 1.5-mu m wavelengths in-plane with the waveguide devices, though electronic, rather than optical, control schemes are envisioned for more complex systems built from these devices. Experiments characterize bit-error-rate performance in the bar and cross states during static and dynamic operation. The all-optical demonstration exhibits the ability of the switch to implement ultra-short transition times (<2ns), high extinction ratios (>10 dB), and lowpower penalties (dB) at a data rate of 10 Gb/s. Further performance improvements are expected by using electronic carrier injection via p-i-n diodes surrounding the ring waveguides. The 2 x 2 switching functionality facilitates the design of more complex routing structures, allowing the implementation of high-functionality integrated optical networ ks.