Considering Facebook paid a whopping $1 billion for Instagram none of us should be surprised that the company wants to turn the photo service into a profitable part of the business, and as expected that profit will come from ads. During a company earnings call earlier today, Facebook CEO Mark Zuckerberg said:
“Kevin [Systrom] has always been clear that we’re building Instagram to be a business. We expect over time to generate a lot of profit from it. We think the right focus for now is to continue increasing the footprint of Instagram and, when the right time comes, we’ll think about advertising.
So while they're coming at some point we really have no idea when or how they will be implemented. We wouldn't be surprised if Facebook places ads in stream in a pretty similar way to how photos appear.
Source: The Next Web