Direct cache access sounds cool, but I'm sort of under the impression that Altera and Intel are playing catchup with the FPGA SoC idea. I believe Xilinx was the first mover by a large margin, though I could be wrong. That doesn't mean Xilinx's Zynq will always be the best product, but it is already for sale right now, is an established product, and works well.
FPGAs with CPU cores have been around for over a decade. The difference is that in the past, the industry has mostly focused on the PowerPC core. Now that ARM has such tremendous popularity, it makes sense to focus on it.
