Comcast is fairly evil, to be sure. But if they're doing one thing right, it's the latest version of their free iPhone app, Comcast Mobile App 2.0.
In this walkthrough, you'll see that not only can you set recordings from your iPhone, but you can do so over the multiple DVRs that you may have in your house. (Note: so far, this function is only available in select areas.) Meanwhile, everyone receives new push notifications reminding you to watch or record your favorite shows...which admittedly sounds a bit useless in the DVR era.