Sigma has been turning the lens game on its head with impressive models like the relatively affordable 18-35mm f/1.8, and now they are joining the adapter pack with the MC-11. While it looks like official information is a little sparse at this point, there will be two versions of the adapter that will work with E-Mount cameras for Canon EF or Sigma SA lenses. This adapter will support all functions of these lenses on the Sony cameras, including aperture control, autofocus, and lens stabilization. 

We'll update when we have more info on price and release date, but if we are to judge based on their other accessories, I wouldn't expect this to be more than a few hundred dollars, hopefully coming in at a lot less. The original link was from DSLR Magazine, but it looks like it has been removed, so they probably jumped the gun with the announcement. It's also worth noting that this doesn't have the optics of a Metabones type adapter — it's just a straight 1:1 adapter. 

Sigma also announced today that they are going to release a firmware update for the Canon/Nikon 150-600mm F5-6.3 DG OS HSM lens on March 11th:

The latest firmware update improves the AF algorithm of 150-600mm F5-6.3 DG OS HSM lenses and further enhances AF speed by optimizing HSM (Hyper Sonic Motor) drive control. 

It is expected to increase autofocus speed by approximately 20%, to a maximum of 50%, during normal shooting as well as when using “Speed Priority” set through SIGMA Optimization Pro.