i wouldn't jump on the x79 platform just yet. x79 is very new and intel still has problems it needs to fix. ivb could come out in april.
http://www.tomshardware.com/reviews/x79-ud3-p9x79-pro-dx79si-benchmark,3111.html
then there is the
vt-d bug that was 'fixed' recently.
and exploding motherboards:
http://www.tomshardware.com/news/Gigabyte-MOSFET-G1.Assassin-2-GA-X79-UD3-GA-X79-UD5,14374.html
iirc [strike]it got fixed by disabling oc.[/strike] looks like the problem was in the bios.
anyway, imo lga 1156 is strong enough to go on till haswell comes out.
you can't get 'the latest', your stuff becomes old the moment you buy it. there is always something new in the future. heck, according to the rumors, sb-e will be replaced by ivy bridge-e by the end of the year.
yet another review of 3820:
http://www.kitguru.net/components/cpu/zardon/intel-core-i7-3820-and-asrock-extreme4-m-review/
chipsets:
for mainstream sandy bridge core i3/5/7 2xxx cpus (lga 1155)- h6x, p67, z68 (and ivb chipsets, according to leaks and rumors. untested.)
sb-e core i7 3xxx (lga 2011) - x79
ivy bridge core i3/5/7 (lga 1155)- h7x, z7x (and h6x, p67, z68 after bios update. still untested.)
ivb-e (lga 2011...?)- x79...?(according to the rumors. untested and unsure.)