Twitter is starting to go on a mobile acquisition binge, as for the second time in one month it has bought out a start-up developer that specializes in mobile messaging. On Friday, Twitter posted a message on its official blog that it has purchased Cloudhopping, a company that specializes in mass texting campaigns for advertisements and product promotions. "Twitter processes close to a billion SMS tweets per month and that number is growing around the world from Indonesia to Australia, the UK, the US, and beyond," wrote Twitter in its blog post. For a company that generates so much usage over the mobile space, Twitter has been surprisingly lax in devoting a lot of resources to mobile phone infrastructure. It simply made its platform open to all developers, and let individual app makers do the work. That is, until recently. Earlier this month, Twitter bought out the maker of the #1 mobile Tweeting app, and this most recent acquisition gives the company a very solid standing in its push to expand the mobile market. As part of the acquisition, Twitter receives all of Cloudhopper's infrastructure, and both of the people behind the small start-up will become official Twitter employees.