Just thought I'd add some recent news on the release date in case it hasn't been said already. This comes via Bean who pointed the magazine article out to me - so all credit to him on this info.
In the latest edition of Holiday Car magazine in Japan they have a timeline for release of the next gen GT-R. Apparently, it will be in the public's hands around mid-2006. Also, I think the mag said that the US release will be at the Detroit Motor Show.
Also, there doesn't appear to be news suggesting that the engine (eg. 3.3l twin turbo, etc.) and drivetrain details that have already been discussed on this board and elsewhere have changed.
I guess there's not much point of waiting for something new if you're in the market for a GT-R.