Product : Citrix, XenServer/6.5, Commercial Edition
Feature : Migration Compatibility, VM Mobility, VM Mobility and HA
Content Owner:  Roman Macek
Yes (Heterogeneous Pools)
XenServer 5.6 introduced Heterogeneous Pools which enables live migration across different CPU types of the same vendor (requires AMD Extended Migration or Intel Flex Migration), details here:
This capability is maintained in XenServer 6.x