Subsequent releases of 4.6.x will be handled by Sustained Engineering through the usual process of weekly patch and monthly public releases. The first patch (4.6.0p1) will be released on December 4, and the first public version (4.6.1) will be released soon after.
The following summarises the 4.5.x to 4.6.x transition plan and which version is going to contain what fix:
Unity 4.5.5 (released on October 13 2014) will be the last public release version of Unity 4.5.x.
All bugs fixed and released in 4.5.5p1 to 4.5.5p5 will be available in 4.6.0p1 and subsequently in 4.6.1.
Please refer to http://unity3d.com/unity/qa/patch-releases for the bugs fixed in the 4.5.5p1-4.5.5p5 patches.
In addition, a few other issues including iOS 8 autorotation are in the works and will be included in 4.6.0p1 and hence in 4.6.1.
The first patch release (4.6.0p1) will be shipped on December 4.
The first public release (4.6.1) will go live soon after 4.6.0p1.
Note that 4.6.0 will use the Web Player released in 4.5.5. New updates to the Web Player (including the OSX 64-bit plugin) will be available in 4.6.1. This version will also be available for automatic updates.
Technically, all bugs fixed with Milestones 4.5.6 on the Issue Tracker should be considered as fixed in 4.6.1 as there will not be any 4.5.6 public release.
Future 4.5.5 patches will be released only when the need arises – e.g. serious issues affecting wider community and/or to honor existing support contracts.
More importantly, iOS 64-bit support will be available in a future 4.6.x release. Learn more
In summary, anyone who would like to ship games with Web Player support with bugs fixed in 4.5.5p1-4.5.5p5 should wait for the 4.6.1 public release. This will be shipped soon after 4.6.0p1. Note that 4.6.0 does not include fixes from the patches 4.5.5p1-4.5.5p5. Also due to complications that could arise from shipping two public releases close to each other, it was decided to drop 4.5.6 and do a 4.6.1 public release instead.