The Symbian Foundation, reponsible for the popular Symbian OS that runs on smartphones, has announced that it will be changing its release schedule to what appears to be a 6 month cycle, according to the images published on their blog :

In the picture, the yellow arrow roughly indicates the time period in which the code for a platform release is available.  The milestones in a platform release are overseen by the Release Council on behalf of the community:

• Prior to functionally complete, the platform grows as new features are added by contributors
• Between functionally complete and hardened the development community focuses on driving up stability of the platform by testing and contributing defect fixes
• After hardened the release enters a more stable phase.  Contributed defect fixes will continue to be incorporated by package owners for around 12 months, but prime focus will be on later releases.