Gelmer and Dodece bring up two very good points.
HD penetration is still light years away from being main stream. This is because of 2 reasons that G & D brought up, convenience and price. First off the price is still ridiculously high that for (i'm in the US, so i'll stick to that) your average family who makes around 35k-45k a year, it's literally 2-3 weeks worth of pay just to enter into the HD market. Since the US as a country is in deep shit in terms of credit, this makes one of the easiest ways to afford HD much less of a viable option. So who is really buying these HDTV's; These HD-DVD/Blu-Ray players? The people who buy these kinds of products whether they can afford it or not.
Obviously the price is one concern for the mass market out there, but the convenience is definitely the biggest concern for consumers. It is not easy for Joe and Deb Homemaker to figure out how to set up there HDTV. They don't know they need HD programming to take advantage of the higher resolution. They are being bombarded by notions of "needing" 1080p, when in reality as long as you Have a 70" TV or less and sit no closer than 10' from it, your eyes WILL NOT be able to see the difference in quality. They don't know these things because it's not intuitive. How hard was it to switch from VHS to DVD? It wasn't. It was all NTSC 4:3 aspect ratio. You didn't have to change your settings on your DVD player or your cable box to match those of your TV. It just did it automatically. On the other hand, it's inconvenient for consumers to try to get the most out of thier HDTV equipment because there are just way too many variables to deal with. It's not just not intuitive.
Until they make it easy and cheap for everyone to figure it out, it will be many years before its adopted by the general public.