What's the value or harm of a literal belief in rebirth?
I think you're right to question the importance of rebirth; the Buddha himself didn't seem to dwell on the concept, though remembering one's past lives does have obvious practical benefits - lots more experience to draw upon :)

Bhikkhu Bodhi wrote a couple of things about the subject you might find interesting:


Dhamma Without Rebirth?
Does Rebirth Make Sense?


As he says in the first link,


  If we suspend our own predilections for the moment and instead go directly to our sources, we come upon the indisputable fact that the Buddha himself taught rebirth and taught it as a basic tenet of his teaching. Viewed in their totality, the Buddha's discourses show us that far from being a mere concession to the outlook prevalent in his time or an Asiatic cultural contrivance, the doctrine of rebirth has tremendous implications for the entire course of Dhamma practice, affecting both the aim with which the practice is taken up and the motivation with which it is followed through to completion.


I've talked about the subject before myself, and the conclusion I make is that it's not that Buddhists believe in rebirth, it's that we don't believe in death - the latter being merely a concept referring to the change from one set of experiences to another. True death only occurs either at every moment or at the experience of nibbana.

In any case, as useful as rebirth may be in reminding us of what's really at stake in our dhamma practice, far more useful is an understanding of the present moment, something that really has little to do with past or future lives.