Gale Porter, a professor at the Rutgers School of Business, warns employers to anticipate a possible spate of costly lawsuits from employees claiming they are addicted to BlackBerries and other personal digital assistants (PDAs).

Porter believes employees who feel unable to turn off their PDAs and cell phones may take legal aim at their employers for so-called technology addictions. Some people refer to the PDAs as CrackBerries.

States Porter: "If companies develop a culture in which people are expected to be available 24 hours a day, then they should be prepared for the physical and psychological consequences." She adds that "workaholism" can be a serious psychological addiction; symptoms include an inability to delegate or function as a team.

The American Physical Therapy Association's Margot Miller uses the term "BlackBerry Thumb" to describe a repetitive-stress injury causing pain and/or numbness in the thumbs and hand. Those who use their PDAs for more than short intervals several times a day are more likely to develop symptoms. She says applying ice, stretching, thumb splints, and cortisone injections are among treatments. In worst-case scenarios, surgery may be necessary.