There is an insane amount of misinformation in this thread.
The bottom line is that you can get good 720p/1080i feeds right now. The HD broadcast spec is restricted such that anything above 1080i would be too heavily compressed and this spec is unchangeable without breaking all existing ATSC tuners. This standard will be more adopted as time goes on and for home use, it doesn't make sense to look to higher resolutions yet. Cable companies are currently in a tight bandwidth crunch and satellite companies also have limited amounts of bandwidth to work with. More efficient compression algorithms may allow for higher resolution video,of course, but people have to be able to see the difference and want it.
There is always work being done toward the next new thing, so you may hear rumblings here or there about new, higher resolution standards to display the current HD spec. This isn't likely to happen anytime soon because it would increase the cost of everything -- from hardware to subscriptions and there are a slew of other barriers (manufacturing would have to shift, cameras for live TV would become significantly more expensive, etc).
There is also the issue of need -- if the consumer can't tell the difference on a 50" screen, why should the consumer want a higher resolution? Right now, depending on viewing distance it can be very difficult to discern between a 1080p and 720p source on a set that can scale to both resolutions well (or change resolutions in the case of CRT) on even 50" screens. I have a nice 50" 1080p screen, and 720p stuff still looks phenomenal.
If the US sticks to its "analog broadcasts to be disabled by 2009" then all broadcast TV stations will broadcast in both HD and DTV at that time. This doesn't mean the source will be HD -- but, as always, the costs of recording in HD are decreasing over time. Right now, a lot of shows are already in HD if they can afford it.
As far as video games are concerned, I can't imagine next generation games not rendered in 1080p. Progressive scan rendering makes sense for games and memories and fill rates should be large enough so that the difference between 720p and 1080p is no longer an issue.
As for which HD resolution will likely become the next standard, I'd bet on 720P since it's the resolution that pretty much all current HD tvs can display.
Actually, 1080i is accepted by more sets than 720p. There are tons of sets that can do 1080i but not 720p, but most 720p sets can take a 1080i signal and downconvert to 720p with no problems. That's why satellite companies (and cable companies) like to focus on 1080i as their signal standard.
