The MySQL Lifecycle Policy determines which versions are actively supported, and for which platforms such support applies.
The basic principle is that old versions are supported for a quite long, but definitely limited period, once they have been replaced by a newer GA version. For example, since the introduction of this policy, MySQL 3.23 and 4.0 have been retired.
The policy contains also provisions for a different kind of End of Life dismissal. When support for certain platforms has been discontinued by their vendors, of the platform is not widely used, MySQL reserves the right to stop building binaries and testing code on such obsolete platforms.
The reason is simple. While hardware can be bought and stored, time is a commodity in short supply, and there is only a given amount of time that our engineers can devote to testing and supporting multiple platforms.
Therefore, it makes sense to discontinue those platforms that have few users, and dedicate some valuable time to new, emerging platforms that are more popular and widely used.

For the above reasons, at the end of 2008, MySQL will discontinue some old platforms:

• MAC OSX 10.3
• HP-UX 11.00
• SCO OpenServer (all versions)
• QNX (all versions)

MySQL will continue to offer support to specific customers in these platforms, but the public builds will be abandoned as of December 31, 2008.

The above decision is based on some vendor end-of-life support, and on our surveys on platform usage.
The intention is to provide a better service to users and customers, by allowing our engineers to spend time on the more widely used systems.