mini versus micro?

One thing that I have been wondering for a while is what the current definition of minicomputer is. It used to be contrasted with microcomputers, the telling difference being a multichip processor implementation versus a single-chip microprocessor [if so, are the POWER1 and POWER2 processors minicomputer processors?] but now, with microprocessors being used in mainframes (and even on-topic mainframes) is this distinction meaningless [i.e. should the designation "microcomputer" in its size/power context be replaced with something else?] and, if so, does the [whatever micro becomes]/mini/mainframe become a question of mass (>700 lbs mainframe, >100 lbs mini, <100 lbs [???]), or history (the HP3000 started life as a mini, therefore the spectrum models continue as minis . . .), or does the venerable minicomputer cease to exist? any other ideas? Scott Quinn