Twitter’s business model is starting to show. An early sign came in April, when the popular microblogging service launched in Japan and the home page for every Japanese user included a big banner ad in the top right corner. Then, on Aug. 7, Twitter made another change, this time in the U.S., by limiting the number of people a single user could connect with, or “follow,” to about 2,000. Most recently, on Aug. 14, Twitter made the biggest move yet to slash costs. It killed outbound message delivery to mobile phones via short message, or SMS, in all countries except the U.S., Canada, and India.
