The number you want is "new household formation".
According to Bill McBride at CalculatedRisk, the reason why housing tends to lead economic recoveries is due to new household formation. When people get a job and move out of their parent's basement and into a place of their own, they stimulate the economy by needing to buy furniture, dishes, get cable service, etc., etc., etc. And drive investment in housing, renovation of existing housing stocks, etc., etc.
10s of millions of single gays aren't suddenly going to buy houses or move into new apartments as a result of the end of DOMA and Prop 8. They might, though, team up and get married and form new households. New monogrammed towels, more consumption on things like movies together, joint investments and bank accounts, adoptions and surrogates for children, etc., etc. And eventually that drives investment in new housing, etc., etc.
Anything that encourages new household formation at this time will help the economy get moving again.
Cheers,
Scott.