A Dead Like Me movie is in production, with many of the original actors but without Mandy Patinkin [also, et] and others. Also, it looks like this is direct to DVD, but may also have sequels [also].
Update 20jan09 @ 4:55 pm:
Dead Like Me: Life After Death is now listed as pre-order, and has a release date of Feb 17th.
As an aside, it turns out the the also now-cancelled show Pushing Daisies was developed from an episode idea for Dead Like Me. [see]