There is a need for Object ID Permanence, currently this need is partially filled by using OSM table IDs, but these IDs are transitory, and can easily change for example when a node is converted to an area, merged with other nodes or even if there is similar nodes in an area.

However not all objects in the OSM DB need a unique ID, and some objects need multiple IDs, I've typed up a wiki page with some initial thoughts on the subject, and using UUIDs:

osm.wiki/Proposed_features/UUID