SM4, presently scheduled for August 2008, will be the last servicing mission for the HST. It includes installation of two new instruments (WFC3 and COS), repair of two others, and other upgrades that should maintain the telescope's unique capabilities through 2013. This is a brief overview of the mission and some of HST's scientific priorities for the subsequent 5 years. Not coincidently, the deadline for proposals for HST Cycle 17 is March 7.