System Information
Mac OS 10.8.5
nVidia GTX 680

Blender Version
Broken: 2.70.5 Hash 48881ad
Worked: don't know

Short description of error
With a Blackbody node connected to a Emission node, AA seems not working.

Exact steps for others to reproduce the error
In the default scene, on the mesh Cube add a Modifier Subsurf Simple and a Wireframe, it's just to see clearly the problem.
In Cycles render, add a new material, add a node Blackbody & Emission.
Hit render and look the result.
Disconnect the Blackbody node and re-render.
Look the difference.
Or
Just open my .blend file ;)