VR Zone reports Intel Sandy Bridge based motherboards may be compatible with the future Ivy Bridge processors. Both chips use the LGA1155 socket, you will be able to use Sandy Bridge into a Panter Point chipset based motherboard without a problem, but it's still unclear which Sandy Bridge motherboards will support Ivy Bridge because Intel hasn't released its cross compatibility guidelines yet.
However, older motherboards and newer CPUs have always been a bit of an issue, although one it seems Intel is doing its best to solve this time around. However, there is a but and this but comes down to the simple point that Intel isn't releasing its cross compatibility guidelines until sometime later this quarter.
This potentially means that current board designs won't be compatible with Ivy Bridge processors. Considering that there tends to be power related design issues between various CPU generations, current motherboards might not have been designed with Ivy Bridge in mind. Of course, this is something we don't currently know and we'll be putting the question forward to the motherboard manufacturers and see what they have to say on the matter.