API portability for ARM Cortex (Xilinx Zynq 7000) with PowerPC (Xilinx Virtex 4)
Well, Microblaze and PowerPC had some level of common API and those devices were developed contemporaneously.

Whether this happens with Zynq is yet to be seen, as everything detailed is under NDA at the moment as far as I know.

I imagine they'll want to keep as much API carry-over as poosible, but it is a very different device (Processor with an FPGA on the side, rather than an FPGA with a processor inside it).