Via Column Two, an article from Brian Buehling on ECM project success.
To the list I would add “Uninformed customer” (or maybe something else a bit less pejorative) who does not recognize the level-of-effort typically required to implement the often-times overly-complex set of requirements.
Some mitigation options for this one include involving the customer early and often, building prototypes that can help confirm a requirement and show the complexity needed to implement it, and sharing experiences from past projects.
Check out Brian’s article for the rest of his list of people “waiting in the wings” to derail an ECM project and what you can do to avoid problems.