The opportunity extends beyond support for x86 devices in that more traditional hardware switches etc. should also work with openflow.
I've found there's lots of OSS around the controller and virtual switches for testing/lab but the only serious openflow agent designed for hardware switches I've found is Big Switch's Indigo[1] it has very limited hardware support.
I see experimental support in OpenWRT - this is very interesting as it opens up a shed load of hardware options.