This doesn't appear to be a big driver update with AMDGPU-PRO 17.10 having been released earlier this month with Ubuntu 16.04.2/16.10 as its primary feature. The new driver out now lists the same changes but also now mentions the RX 500/570/580 support.
The driver can be downloaded from AMD.com. My Radeon RX 580 Linux testing will begin in a few hours with the card being out now for delivery. Stay tuned.