The flood of imagery and data from NASA's Mars Reconaissance Orbiter (MRO) has started, and there are some great pictures from the HiRISE camera available on-line. The picture shown here (from the HiRISE blog) compares HiRISE imagery of a crater with imagery of the same area taken by Mars Global Surveyer, until now the highest available resolution imagery of Mars. The difference is beyond striking!
The best way (so far?) to view the HiRISE imagery is with a Flash application called Zoomify that is available on the HiRISE web site, so far with 11 HiRISE Mars images. When you use your mouse to zoom in and pan with this application, you soon get to a point where the image looks pretty detailed. Then you zoom in some more and see features as small as ~1 meter -- detailed views of all sorts of features such as a field of rocks with clear shadows as in this image. Amazing stuff.