For Twitter, it is good to be the younger sibling in the social media club. It gets to follow in Facebook’s footsteps. It gets to avoid its mistakes. Facebook had to push the boundaries and take in harsh criticisms. Twitter gets the benefit of the doubt and the advantages of hindsight. Case in point: Twitter made it official this morning that it will be launching app install ads through its MoPub mobile ad marketplace. With considerable enthusiasm, the announcement talked up the creative and measurement tools available to developers in this new offering.