Grumpy_Mike:
tantalum are rubbish for decoupling. So are most electrolytics.
They are both good for bulk decoupling, the low frequency stuff. However, tantalum capacitors used in power supply decoupling are a fire hazard as when they fail they tend to fail short circuit and burst into flames. That is why you won't get UL approval on a system using tantalum capacitors on a power supply.
I'll stick to ceramic+polyester...