The twin 10-m telescopes of the W.M. Keck Observatory have now been in operation for almost a decade. The original complement of first generation instruments remains in use (NIRC, HIRES, LRIS, and LWS) and all second generation instruments have been commissioned and are in regular operation (NIRSPEC, ESI, NIRC2 and DEIMOS). Both telescopes are equipped with Adaptive Optics (AO) systems, but only Keck II is equipped for AO science at the present time. Several detector upgrades and new third generation instruments are in progress. The blue side of the LRIS double spectrograph received two new E2V 2k x 4k CCDs in July 2002 and a 3-CCD mosaic upgrade to HIRES is scheduled for commissioning in mid-2004. An upgrade of the LRIS-R CCD is planned for completion in late 2005. The near-infrared integral field spectrometer for AO (OSIRIS) has passed critical design review and is in advanced fabrication, and studies for a near-infrared multi-object spectrometer are in the preliminary design phase. An Atmospheric Dispersion Compensator (ADC) for LRIS is currently under development. Other major developments include regular operation of the Keck-Keck interferometer, and the first successful closed-loop operations with the Laser Guide Star on Keck II.© (2004) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.