Operating system: Windows 7 x64
Graphics card: NVIDIA GeForce GTX 580
Short description of error
With multiple objects in Pose Mode, Select All selects bones belonging to objects which have the Hide Select flag set.
Exact steps for others to reproduce the error
Create two armatures, put both into Pose Mode, set Hide Select on one of the armatures via the Outliner. Attempt to select a single bone in the hidden armature with a mouse click (unable to select, as expected), use 'A' to Select All (bones in the hidden Armature are selected).