It appears that both OEM's are moving over to Optical Smoke Detectors.
I have seen cases of Durians, fog (generated by the aircon) and insecticide setting the detectors off. There have been two cases of cargo fire bottles being discharged on landing/taxi-in in Hong Kong in the recent months - one SAA, one CPA, both A340-600's.
The fine fog that gets generated when the highly humid air gets into the cargo hold has been blamed in both cases.
Airbus are investigating, suggestions from them to ignore the warning for 10 seconds are not being warmly received, but looking at the pilot feedback, it looks like a 10 second confirm time is sufficient to weed out the spurious warnings and not have a significant effect on the outcome if it is a real fire.