I agree with those who have said the likelihood is small for trading down. Seems like every team just in back of the Jazz recognizes the talent pool is pretty equal at that point and has said they're looking to trade out or down.
All the GMs are giving out signals that it's time to start discussing trades. I think teams would do that any year outside the top 3. The question is whether a team like Boston or the Lakers would get a better player in a trade than they could draft where they're sitting.
I don't think the Jazz will get offered a player that's significantly better than the talent they'd draft at #5 (Vonleh or Smart). Could happen though, and the Jazz seem to be exploring every avenue.