Well $600 is a sound investment in a video game system, but I do think the system is going to be fantastic over time. As for your question regarding a Jak & Daxter or Ratchet & Clank game, there is rumors regarding both games being in development already for the Playstation 3.
Jak & Daxter: The Lost Frontier is rumored to be in development for the Playstation 3. Not much else is known about the game other than it will be the second game in the series (Jak X being the first) to offer online game play.
There is also a rumored Rathet & Clank game being developed for both the PSP (Ratchet & Clank: Size Matters) as well as a still-untitled Ratchet & Clank game for the Playstation 3. It would appear that even if these games are in fact in development, and I'm fairly sure they are, they are still likely very early in development.
As for your HDTV question, 720p is still great for the Playstation 3 system as many of the early games only support up to 720p anyway. There will be 1080p capable games coming out for the Playstation 3, but these games will still look terrific even in 720p on your HDTV. So no need to worry. : )