I think it would be a good option the ability of download from www.blender.org besides the official version, the latest bugs fixed (daily?, weekly?) , only fixed bugs without adding new tools.
I think the “a” versions could disappear and would be more dynamic update of Blender
also extend the stable releases and make updates of new tools “quieter” for developers and users.
Download Blender 2.66 production stable / rev.22-2-2013
Bugfix: #34351, #34355, #34370…
Not sure if would be possible to automate the current Builbold platform for build Blender only with fixed bugs, or would be too much work for the developers.