It's not "This Old House", but the Do It Yourself network just completed shooting their first series in high definition. "Creative Juice" will start airing their 26 half hour episodes featuring various small home crafting projects on February 6th. I assume the high def versions will follow later in the year as Scripps launches two high definition networks. They shot the series using the Panasonic Varicam in 1080i.
The shows post supervisor, Reed Fenton, described their main problem as having enough storage space for all the HD footage (11 terabytes), they should've just grabbed some HVD's and been done with it. We can look forward to more high definition content as prices drop for equipment and smaller producers like Castle Creek can make use of it.