The latest Nielsen Smartphone Penetration report indicates that 25 percent of U.S. consumers now own smartphones, and marketers who understand the value of reaching Americans on their mobile devices may want to make their social campaigns mobile-ready. Compete’s Smartphone Intelligence Survey shows checking social sites is now routine for mobile device owners.

The study found that 33 percent of smartphone owners who have Twitter accounts send tweets mainly via their smartphones. Moreover, one-third of these consumers prefer to read tweets on their mobile devices, indicating brand tweets may be better received when read via phones.

Smartphone Facebook users were even more enthusiastic about accessing their accounts via their mobile devices. Two-thirds of respondents say they are increasingly using their smartphones to read their news feeds. Additionally, 60 percent use their devices to make status updates.

“Based on our findings, I recommend marketers start thinking about new ways to maximize consumers’ use of smartphones on social sites, as mobile adoption will likely only increase with time,” the Compete blog quotes Danielle Nohe, director of technology and entertainment for the firm, as saying.

Marketers may find insight on how to capitalize in mobiler users’ interest in social check-ins on the recently released mobile marketing best practice guide from the Interactive Advertising Bureau.