When is Blender 2.5 getting out of bata:(
No-one can tell you because no-one really knows for sure.
From this developer meeting, we learn that:
First stable 2.5 version (2.57) is still planned for March. Priority remains on bug fixing and to-do items.
So very soon!! 
The most reliable release date I’ve come across is “When it’s ready”.
However, judging by the versioning conventions, 2.57 is supposed to be the first stable release as stated by Guiseppe. It seems that this number is being reserved as the most recent beta was called 2.56a. Usually, the letters are only added for sub-releases and it is rare for a Blender version to have the ‘a’ in it’s version number since at the time of release, it is not known that there will be any sub-releases.
Considering the above, the dev team might be expecting further sub-releases of 2.56 before the stable 2.57, but the stable release should be fairly soon. This gives them 2 whole releases (2.58, 2.59, plus sub-releases) to add features before Blender 2.6. 