You should take a closer look at Xilinx's tech docs (there are a lot): http://www.xilinx.com/products/silicon-devices/soc/zynq-7000... - it uses ARM AMBA for interconnect.

FWIW, Parallella uses a very similar chip (ZYNQ7010 vs 7020) and lists the interconnect bandwidth as 2.4GB/s so I'd expect it'd be around there.