The Mars Phoenix Lander is expected to launch on Saturday. There's a nice article in today's MIT Technology Review update on the technology and scientific instrumentation that Phoenix is packing. It may lack wheels and have mostly been built out of spare parts from earlier Mars missions (one crashed, one canceled), but its ability to dig deep (up to half a meter) into Mars' soil and to analyze what it finds there is really unprecedented. I knew about the "oven" that will carefully heat samples to record and analyze the gases that are released, but I didn't realize that it also carries both an optical microscope and an atomic force microscope (AFM) for very close examination of soil samples.
A simulated Phoenix is shown just before landing (using an add-on in Orbiter).