Robert,
In the past, when the government committee tried to create standards for high definition (ATSC) there was a war, basically between the computer folks and the television folks. Neither won. Instead the committee created seventeen (or eighteen?) standards including 720, 1080, progressive and interlaced at various frame rates.
These standards will exist for a long time, because they really only come into effect next spring, when the digital transmission is mandated to begin.
You need not fear buying any HD camera as the formats are convertable and transcodable. The biggest danger, as has always been the case is the longevity of the recording format, and that which most prosumer cameras use, HDV is the most flawed and most likely to disappear in the near future.
JS