Hot on the heels of filing for a $5 billion IPO, rumor has it that Facebook could introduce in-line ads into its mobile interface as early as next month. While few details are known at this time, it's said that these ads will show up directly in users' timelines as "featured stories."

There's no word if this will affect both the mobile web version of Facebook and mobile apps alike, but it looks like we won't have to wait very long before finding out.