As said, they are both backwards compatible so if you upgrading you may as well futureproof yourself.
Also, isn't pci-e 3 due out next year as well?
Oh for goodness sake lol, not another thing, everytime I think of upgrading something else crops up... I was going to wait for SATA III and USB 3.0 and now I'm reading up on PCI-E 3, being twice as fast as PCI-E 2... yet another thing to wait for or is it just another pointless upgrade?
Generally if you wait for new technology you will never actually buy anything. Product gets released all the time and unless you have pots of money around your ankles you will never be able to keep up.
why are you interested in i9. it is basically a die shrink of i7.
As they are getting rid of i7 920 and 940. I7 will be hugely expensive and I9 even more so. So I don't see why you would be interested or waiting for it.
Probably can't find it as intel probably haven't said exactly when. but it is expected soon after Core i5, so probably q1 2010.