a) if you recycle the bulbs, the mercury is recovered.
b) I doubt that more than 1 in 100 bulbs are broken in the process of installation/removal. I have to admit, I broke on installing it.
c) The mercury emissions from coal fired plants is often only considering air emissions. I don't know if this is the case with the above quoted numbers. Air pollution control hardware is 90% efficiency, so that said, nearly 10x the amount of mercury is captured in the ash and landfilled in toxic waste landfills or sequested in concrete blocks.
d) Mercury is only one of the pollutants from coal. Sulfur dioxide, uranium, thorium, lead, are also pollutants from coal.
e) Coal mining has killed tens of thousands of people over the years, both with mine accidents and black lung disease.
f) Coal mining has created huge environmental disasters in the past, and even with todays environmental considerations continues to create a lot of torn up mountains, and culm.

For me the best thing to do is to first turn off lights when not in use. Many people do not do this. Second, use lower watt bulbs, or dimmers. Third, you only need to install CFL's in the top 3 or so lights you use most frequently.

Last but not least, take your incandescent bulb, turn it upside down, and look at the bottom. You will see a drop of solder on most bulbs, which is lead.

To produce purified mercury in a CFL, the extraction process releases about .4mg for every milligram produced into the waterways, atmosphere, and soil as waste. This is a well-established worldwide average that includes many processes, both crude and hi-tech. This means that the 4mg in the CFL actually represents 5.6mg of mercury that enters our environment. Adding the coal energy contribution means the CFL's account for 7.1mg versus 7mg for incandescents.

Add to this the Lawrence Livermore Laboratories study that concluded that the average CFL life is reduced by 50% where they are turned on and off every hour and the mercury contribution goes up to a whopping 13.6mg or so. The reduction in incandescent life for the same use model (20%) does not affect its mercury consumption and it remains at 7mg or so. The same study concluded that a 30 minute use model reduced the CFL life by 85%…which would mean the CFL would use ..gulp.. 38.8mg of mercury by the time the rated life of the CFL was reached…compared to the 7mg used by the incandescents.

These are real numbers. CFL's can offer significant energy savings in general. However, the thrust of a lot of pro-CFL articles in addressing mercury emissions is completely unfettered by reality by claiming less mercury pollution is generated through CFL adoption. CFL's will use a lot more mercury than incandescents, period. How unhealthy that mercury is is a valid debate, however.