First users found out yesterday that 126.96.36.199 is upgradable since "release" of Jolla C device at the community event.
This is not official, no complains on bricked phones please.
We have many people over at TMO who successfully updated with no or slight problem though. Only try if you are desperate for some tinkering, know how to unbrick and generally what you are doing if typing into console
ssu release 188.8.131.52 version --dup
There is also a lower 184.108.40.206 some users upgraded to. It is possible to take the steps from 220.127.116.11 to 18.104.22.168 to 22.214.171.124. One problem reported was incomplete update. If you encounter any problems after first attempt, try again to possibly fix it.
Imho the update optimized in regards to Alien Dalvik "niceness" and Browser stability. If you are unsure, please wait for official release and changelog!