I looked at about 1000 sites (the week of 1/26), and came up with only two sites where YouTube was a visible part of their home page. The sites were:
1-800-Flowers with their "Greatest Love Story" contest and
Urban Outfitters who has used YouTube for several weeks in different capacities.Most of the DRTV sites use some type of streaming video as part of their user experience. For example see:
YouTube in Emails
Shari's Berries used a YouTube video as the prominent feature of their 2/7/08 email. Subject line: "Watch the Video, New Gund Frog Sings My Girl, Save 20% ".
Landing Page (click to enlarge screenshot)
Here's a live link to the landing page if you want to watch the video.
If you are interested in using YouTube on your site, see also
STORES Magazine: Do YouTube?
YouTube for E-Tailers: Tips, Camcorder Reviews
Shop.org Blog - Look whos's marketing on YouTube!