The editor of the Washington Post Sunday crossword, Fred Piscop, has announced that the feature is being discontinued as of March 31, 2008.
In a statement to cruciverb-l, Piscop cites financial reasons for the discontinuance of the crossword.
Piscop has enough puzzles to cover the remaining time period so he is no longer soliciting contributions. Meanwhile, the Post will begin carrying Merl Reagle's puzzle on April 7.
EDIT: Talked to Robert about this today and his response was, "Sudoku has claimed its first victim."