I'm running some speaker wire in-wall for my mains... Right now, I have the sub cable bundled up with the speaker wire. This is the sub cable description from monoprice:
RCA CL2 Rated Cable - RG6/U 75ohm (for S/PDIF, Digital Coax, Subwoofer & Composite Video)

They are running together for about 20'... Any problems doing this?

Thanks,
-Todd

Not at all.

Awesome!

I really didn't want to re-pull that cable... :)

Thanks!
-Todd

As long as there isn't any power running right next to them your fine, all the low voltage stuff tends to play nice together.