If you have one of the current Quads I would not get a core i7 yet.
The new boards that support the core i7, (the x58) allows sli or crossfire setups which is nice. Makes the battle of pairing up your graphic cards with your motherboar a lot easier. Like everyone else has been saying price is through the roof on this stuff. Tri-channel ddr3 is going to be pretty expensive. If your running sli or crossfire then you probally arn't on a tight budget so that would be the only real reason if your a gamer to upgrade to this option. If your a single gpu user, then I would wait till price comes down and the new P55 boards come onto the market.
If you're not a gamer and using this for encoding and stuff, then you will see a larger improvement in preformance than buying this for gaming. It might even warrent a reason why to get this on release day. Intel decided to target the bussiness market and produce the core i7 to fancy their needs. I am not saying that this will not increase gaming preformance but that the increase will be much more suginficant for bussiness type applications. Intel decided to do the integrated memory controler which lowered the amount of l2 cache the processor needs. This is what games rely on.
A few prelaunch bench marks though have noticed a large increase in gaming preformance however. This is mostly on systems that are running top end gpus in sli or crossfire. For gamers unless you are running tri-sli or quad crossfire then wait till the p55 comes out. There is not enough of a preformance increase to warrent getting the core i7. The cpu itself is about the same price of the quad's currently on the market but those will drop in price soon and the core i7 uses that expessensive ddr3, which is really overkill for ram when you do the math.