The story is a little more complex now, and actually was kinda complex then. The GF 6 & 7 and R9700-X850 all could do integer HDR + MSAA, but couldn't do OpenEXR style FP16 HDR with AA enabled only the X1K could.
Now there's the issue of whether hardware AA will 'ruin' the HDR effect or not and whether it needs to be shader based AA. To me this issue is nit-picking and considering the performance hit, not worth it at this time.
For the general issue the shortcoming of the GF 6 & 7 for HDR+AA has be resolved in the GF8, however you still can't enable both in many of the apps out there and you must still force it in the ControlPanel (just like on the X1K/HD2K).