Instagram, a hugely popular iPhone photo-sharing app, has hit a new milestone. Just 9 months after it launched, more than 150 million photos have been uploaded to Instagram.

Users are now uploading and sharing 15 photos per second using Instagram — that’s almost 1.3 million photos per day. There are now more than 7 million users on the photo-sharing service, including Justin Bieber. That’s pretty spectacular growth, given that there were 5 million users in June, with the total number of photos nearing 100 million at that point.

Here’s Instagram photo number 150,000,000, which was uploaded by a user called janefot:

Instagram photos have been taken at major events such as the World Series and the Grammys and some photos uploaded to the service have even been featured on national news broadcasts. In addition to Bieber, many brands and celebrities are using Instagram, such as Moby and “NCIS: Los Angeles.”

Several companies, such as Postagram and Keepsy (which recently launched a gallery of top Instagram users’ photos), enable you to create postcards or photo albums from your Instagram photos. This highlights the fact that Instagram has created a healthy ecosystem where third-party developers can create cool services using Instagram’s API.

This is all very impressive, especially when you consider that Instagram is only available on iPhone, iPod touch and iPad devices. When the service launches on Android, the popularity of Instagram is likely to skyrocket.

If you have not checked out the app yet, you can download it on your iPhone now.