Yes, the Object Enabler is only required to display custom Civil 3D objects - like pipes, structures, surfaces, C3D labels, etc. You don't need it to display plain AutoCAD entities.
Unfortunately, the Civil 2011 Object Enabler is not yet available... it should be shortly.
In the meantime other options are described in the ReadMe:
1. Turn on PROXYGRAPHICS, or
2. From Civil 3D use Export to AutoCAD to create a separate file to bring into SSA.
Once the OE is available you shouldn't have to do either of these.
I hope that helps.
Thanks,
Charlie Ogden, P.E.
Charlie Ogden, PE
Product Manager