Well, good to go only for now I would say.
Although the vulnerability in Windows has been patched, it only means a system can't be hacked through it anymore.
There are of course other ways to spread this ransomware.
The code can easily be changed a bit and it will (at least not now) not be detected by the av's that added detection as the detections added to them is "signature" based.
Also the "kill switch" in this version can easily be removed or changed.
https://technet.microsoft.com/en-us/library/security/ms17-010.aspxI know that for XP a patch was released yesterday, don't know about the other not supported Windows versions but I guess there is a patch for them as well.