Some great discussion over at JoomlaTools about when the end of the life cycle should be for Joomla 1.0.
sdlc
CIO Insight: How to Manage Application Enhancements
"One of the endless challenges for a large corporate software engineering organization is to develop an effective process for handling the steady stream of small changes, fixes and enhancements that seem to accumulate around installed software, both custom developed and Commercial of the Shelf (COTS)—no matter how good it is initially. Typically, these changes can be handled by a single engineer, don't require much resource or elapsed time and are generally pretty well defined. Users know that they are not asking for much, and don't, therefore, expect to have to wait very long to get their change request implemented."

