The Prismiq MediaPlayer seems like the convergence device I've been looking for. http://www.prismiq.com/products/
It connects to your home entertainment system/home theater system and your home computer network (wired or wireless) and allows you to stream media files, both audio and video, to your entertainment system.
I see one of these devices in my future, along with a SageTV computer with 3 Haupauge PVR-250s. With this setup I can put my big and relatively noisy PC in the basement, happily recording TV for me, while I watch the recorded files on my home theater (HT) system.
Now wouldn't it be COOL if somehow the devices integrated together? I could both control the Sage TV system from my HT system and use Sage's time-shifting functions. This seems to me to be the ULTIMATE solution. (Maybe it would even create much more demand for both SageTV and Prismiq, hint, hint, hint...)