Certain light bulbs, old and new, require special handling to reduce toxic exposures. EPA provided guidance for old fluorescent bulbs that contain PCBs on Dec. 29, 2010, and updated its guidance for current generations of compact fluorescent bulbs (CFLs) that contain mercury on Dec. 28, 2010. Both announcements provide important fodder for consumer-awareness stories.
- Old fluorescent bulbs and PCBs: EPA PCB information;  Dec. 29, 2010, EPA press release. 
- CFLs and mercury: EPA's Cleaning Up a Broken CFL;  Dec. 28, 2010, EPA press release. 
The old fluorescent bulbs with PCBs were installed prior to 1979, so your general target for covering this issue would be buildings built before then that have not had a complete lighting retrofit, such as schools (which are the primary target for EPA's recent announcement), hospitals, government buildings, factories, stores, offices, and homes. PCBs, which are persistent, toxic chemicals that can cause a wide range of health problems, can leak from failing ballasts that are part of the light fixture; if they haven't already failed and leaked, they will.
Removing the old fixtures requires special equipment, procedures, and conditions in the building, which EPA has specified. It's possible to get federal, state, utility, or private sector funding help for these projects.
CFLs that break will spread mercury vapor into the environment. This has been known for some time, and cleanup parameters have been developed. EPA has updated those, and they also are applicable for many other types of bulbs, including bug zappers, tanning bulbs, neon bulbs, and high-intensity discharge bulbs.