One of our major complaints about the SD1 was its squat, ungrippable design. Panasonic addresses this in the still-smaller SD5 with the gradually upsloping body. In practice, I did find it easier to grip than the SD1.
2 of 3 Panasonic
In addition to a resolution bump up from the SD1's 1,440x1080 to 1,920x1080, the SD5 also comes in a shiny black finish.
3 of 3 Panasonic
The SX5 outdoes the slightly older DX1 by adding support for SDHC recording in addition to DVD, and ups the resolution to 1,920x1080.