Is Beryllium Oxide still used in the industry?
Yes, it's still used in Apex's range of high voltage amplifier ICs - still a current and popular line of chips for driving, among other things, piezoelectric transducers. For example, the PA95; its datasheet says:


  The exposed substrate contains beryllia (BeO). Do not crush, machine, or   subject to temperatures in excess of 850°C to avoid generating toxic fumes.


These chips can drive large currents at high voltages and therefore need great cooling capability. I guess BeO is just too good a heat conductor to replace, despite its toxicity.