Not that I am aware of. The Apple TV is a terrific, low power and highly capable media player. But, its a bit on the low powered side for use as a media capture device. A Mac Mini is much closer to what you are looking for and can easily be expanded to provide PVR functions.
I'm an old Sage TV user from the version 3\4\5 days. I had a Linux server running quad tuners and serving multiple Windows computers and extenders. I have to tell you, I'm so glad to have left that piss-poor piece of software behind its not even funny. I switched to Windows Media Center during the Vista days and kept using it through Windows 7. I just picked up an Apple TV, a separate Bluray players and retired the HTPC. Honestly, there's not been one day when I've looked back and genuinely missed any of the features the HTPC provided. Was it more capable? Sure. Was it more hassle? 10 x more problems and complications. Heck, my love life has improved now that my wife can use the TV.
As always, ymmv.