Hope you like ads when you tweet from your phone. Twitter announced Monday that it acquired the mobile-ad firm MoPub, the latest move in an effort to beef up revenue ahead of its planned IPO next year. Both MoPub and Twitter confirmed the deal, but would not comment on the reported price of $350 million. MoPub automates the buying and selling of ads, meaning that Twitter is also moving toward being involved in selling ads in the mobile world and not just on its own properties. Twitter said it generates the majority of revenue from ads on the mobile sites it owns, as opposed to from the desktop Twitter.com.