You can configure direct physical I/O for network and FC disk in I/O domain today. But not for guest domains.
1) LDoms 1.1 and Solaris 10 update 6: the guest domains can have direct access to NIU (Network Interface Unit, 10Gbit on-chip ethernet of T5120/T5220). The feature is called Hybrid IO NIU.
2) For generic direct IO to PCI-E devices in the guest domains, it's in our roadmap of future releases in CY 2009.