This is certainly a hint at a monetization strategy. Seriously! Thousands of people would pay for virtual goods like this - especially behavioral/functional virtual goods that influence how many people see my tumblog.
Virtual items are emerging as a strong alternative to advertising for social media. The quote above hits the point home: people would pay for this! However, platforms needs to open up. I am not sure currently whether it is possible for a third party application to provide virtual items for an user's profile page. For a vibrant virtual items industry, we need that to happen.
Alternatively, I wonder if there is a demand for a light weight app that adds a layer around your pictures. The user can then controls how his/her picture can be integrated with other applications, using the layer as the door.
Anyway, I am intrigued by the tumblr experiment and look forward to seeing how it will develop in the months ahead.