I'm very Happy for my gay friends,unfortunately I'm not sure how much it's going to change here...Missouri has a state DOMA in place,which at the moment complicates things...
Immidiately, gays that get married in an equal rights state get federal benefits even if they move to Missouri .. regardless of what missouri wants or doesn't.
In the long term the case precedent and text of the decision on DOMA can be and will be used by people in missouri to sue the state on equal protection grounds to get those laws overturned.