I was watching TV the other night (I have Dish Network) and I saw a commercial for placing targeted TV ads on Dish Network through Google TV ads. I checked out the Google TV ads info (including watching a really quick informative how-to video) and discovered that is built along the sames lines ad AdWords but for TV. You can pick the regions targeted, the shows who's audience you want to target, the length of your campaign and your CPM (in this case, cost per tv's the ad is shown on).
In terms of creating the ad, they offer you a variety of options from bidding to their community of ad producers to creating the ad yourself (as long as it meets their editorial and technical guidelines) to other less technical and possibly lower quality options.
Now, let's say you are developing an online community for baby boomers who are contemplating retirement. Your community is going to cover everything from health & fitness, investing, vacations, estate planning, etc. Would you include a TV campaign as part of your strategy at building the online community knowing that you can focus your advertising on the TV viewing habits of your target market? Considering the inexpensive video HD video cameras and editing software available that can be used, I would take a shot at it as long as I had a budget and had reasonable expectations.