It is still a learning process for the new Firefox rapid release schedule. Earlier this month Mozilla Developer’s News blog explained the difference between the merge and release dates. To sum it up, the dates show on the release page (as well as those posted here) are the date the code is being merged on to the particular channel. The actual release will be around 1-week to allow for testing to ensure the release is stable enough for public consumption. This however only applies to Nightly to Aurora and Aurora to Beta. However, for ‘final releases’, the date listed for a version is the actual release date.

• Firefox 5 is to go the Beta channel on May 17th. The code merge has happened and we should expect to see Firefox 5 available on the Beta channel sometime next week.
• The final release date for Firefox 5 is June 21st and that is the day it will be released. The actual code merge will take place about a week prior.
• Firefox 6 is suppose to be moving from the nightly channel to the Aurora channel on May 24th.  Since Aurora is still very developmental (but more stable than Nightly) the actual release to the Aurora channel could be anywhere from 1-day to 1-week from the merge date.

Starting this week, there will be a clarification added to the release recaps for Aurora and Beta builds.