I remember reading an article some time ago (whose author's name now escapes me) about killing projects. Being part of an internal design team that works on various projects sometimes for months, I find this a particularly important issue.
How do you tell a group of people the work they've put their blood, sweat and tears into for the past few weeks, months or years, is not important anymore? How do you prevent team morale from slumping to painfully low levels? How do you prevent brilliant minds from leaving the group?