sorry i misread your post. I think if you have time warner branded earthlink cable internet it is not capped at least yet... of course if it's comcast branded earthlink then their is a cap that i think was just recently implemented.
It really just depends on where you live. IF the cable provider in your area is time warner then you would get earthlink that runs over their cable lines etc... You should check on earthlink's site at earthlink.com that will tell you what you may qualify for, or you could just give them a call, they should know which territory your in.