The main motivation for this change is to reduce the amount of time between releases and make them simpler, making us able to deliver new features faster to our users while keeping if not improving the current quality.
The time elapsed between big releases (4.12, 4.13, 4.14...) will be of 3 months (instead of 6) having the following structure:
All the freezes will be effective the day of the branching, this include:
Since we will be decreasing the amount of time for testing, it is specially important that only features that are reviewed and stable are merged into master. Saying it in another way master should be always in a state where we can make a release from it.
If you had plans for 4.12 already, keep them! Even though 4.12 would be released 3 months sooner than it was planned, 4.13 will be released around the time (Mid Jan/Feb 2014), so no need to re-adjusts already made plans. Said it in another way, instead of having 1 release of 6 months we are having 2 of 3.
Not much changes besides the fact that releases become way simpler since we'll have 1 freeze day where everything will be frozen, instead of having different days spread across the release cycle.
Additionally missing a freeze becomes less important since releases will be done more often.
There is NOTHING preventing us to do more minor releases if we have people taking care of them, exactly as it happens right now (we have had un-scheduled .5 and .6 releases)
While there will be only one month to translate new or modified strings, the amount of changes in every release can be expected to be minor as well.