Does the quote "a plague on both your houses" have any significance in the play of Romeo and Juliet?

Mercutio utters this line -- "A plague o' both your houses!" -- after he has been killed by Tybalt.  Tybalt came looking for Romeo in order to challenge him to a fight because he was offended by Romeo's presence at the Capulets' big party the night before.  When Tybalt eventually finds Romeo, Romeo has just come from marrying Juliet -- Tybalt's cousin -- and so Romeo refuses to fight this man who he is now related to, by marriage.  Mercutio, not knowing this, interprets Romeo's refusal to fight as a "dishonorable, vile submission" (3.1.72), and he fights Tybalt on Romeo's behalf.  Romeo comes between them in a well-meaning but ill-advised attempt to stop the fight and promote peace, and Tybalt is able to stab Mercutio under Romeo's arm.  For several reasons, then, Mercutio feels that his death is actually the fault of both Romeo and Tybalt: as he lays dying, he curses both "houses," or families, for their roles in his death.  He curses each family to have some tragedy, and, obviously, both families do experience tragedy when their children -- Romeo and Juliet -- kill themselves rather than live without one another.