"The king also said to Shimei, 'You know in your heart all the wrong you did to my father David. Now the Lord will repay you for your wrongdoing. But King Solomon will be blessed, and David's throne will remain secure before the Lord forever.' Then the king gave the order to Benaiah son of Jehoiada, and he went out and struck Shimei down and killed him. The kingdom was now firmly established in Solomon's hands." NIV translation
Shimei's talk was cheap in that he did not back it up with action. Solomon made it clear to him that the judgment that was coming to him was from God because of his treatment of God's chosen kings. He paid the penalty with his life and the last of the enemies of David and Solomon were dealt with.
We are reminded that our walk with Jesus is more than just an idle promise. When we accept Him as our savior, we accept the fact that He has purchased our lives and we no longer belong to self but to Him. Our actions will bear witness as to whether our conversion was merely cheap emotional talk or if we truly know Him as our savior.