Dispel magic can dispel any spell, unless explicitly stated otherwise. As detailed in the rules, casting dispel magic on a permanent magic item will only disable it temporarily, except in the case of potions, which are destroyed.
When cast on some unique magical effect in a dungeon or otherwise found during adventure which is not covered by the “spell” or “magic item” category, it is up to the DM what effect dispel magic will have. It is possible that the effect will be disabled for a round, for a longer period, or permanently. In such cases, a caster level equivalent of the effects power must be keyed by the DM so as to be able to determine dispel chance in the case the spell is cast.