Is there already a register of prefixes used in plugins etc.? (As suggested in one of the Codex pages. A quick Google search hasn't revealed one, but maybe I was looking for the wrong thing.
A simple register - which plugin authors could check, then register their 'own' prefix - would further avoid the possibility of function conflicts etc. This prefix could I suppose also be used on custom fields etc.
Sorry for wasting 'ink' if this facility already exists, and kudos to those who thought of and implemented it! ;-)