I know they are not out yet, but will ivy bridge boards be back compatible will sandy bridge, I know they both use socket 1155 and I know some current z68 mobos are IB ready and others after a software update. my current mobo sucks and I don't need to upgrade my i5-2500k
according to the recent leaks/rumors, one can use an sb cpu with ivb pch e.g. z7x or h7x because they're both lga 1155 compatible. but one would lose ivb cpu-specific features such as pcie 3.0 lanes, intel hd gfx 2500 and 4000, quick sync 2, supporting up to 3 displays, default ddr3 1600 ram support etc. this is all speculation, though.
according to rumors, all z68 mobos can support ivb, so can h61, h67 and p67 boards. only b and q series motherboards don't support ivb.
you can always change your motherboard to another one with z68 pch. besides, intel doesn't have good history with backward compatibility. so it is uncertain how ivb cpus' compatibility with sb boards and sb cpus' compatibility with ivb boards would work out in reality.
Ivy bridge must be compatible with current Z68 boards. A lot is in stake now since if something goes wrong than no one will trust Intel and the rest of the motherboards manufacturers around the world.
BTW there is no reason for Ivy not to be compatible because Ivy bridge is nothing but a Sandy Bridge in 22nm packaging. It is the same processor and same architecture just made in a reduced DIE size fabrication process.