This issue of IT staff retirement is emphasized even more strongly in the recently released Boomers Bid Farewell, part of a major report by Computerworld on IT hiring and employment trends. Other good takes on the subject is CIO Magazine's Beating the Boomer Brain Drain Blues and ComputerWorld's 'Perfect Storm' On Horizon for US Labor Market.
The basic idea of these articles is that departments such as IT need to be prepared for a time when major chunks of their management and technical labor are no longer working. Part of the solution is intelligent succession planning; this has long been a topic in Human Resources literature. Also getting more attention is the need to transfer the knowledge and expertise from older workers to younger workers through a combination of documentation, training, data extraction from email and other communications, blogging, interviewing, workshops, consulting, and other knowledge transfer initiatives.