> the 440 has overlay available to it, the 460 still has no h/w acceleration currently

In case the single onboard-SATA port suffices, you can put a Radeon 9000 or 92x0 into the PCI slot and have overlay as well as 2D and 3D hardware acceleration when running OS4. Besides, I think that the Radeon HD drivers for OS4 do support 2D hardware acceleration.
But the driver situation on OS4 is not so much relevant for running MorphOS on the Sam460 anyway. MorphOS currently supports more and faster Radeon 9xxx cards in 2D and 3D than OS4 but lacks support for anything above.