In a blog post, Facebook just reminded us that its users upload 300 million images a day.

That's a staggering figure, showing Facebook's utter dominance of the online photo-sharing field.

It's also not a new one: Facebook gave the same 300-million-photos-a-day statistic at the end of last year.

Rick Armbrust, a Facebook business-development manager who wrote the post, was also careful to highlight all the third-party apps like PicCollage and Hipstamatic that are used to upload photos. Facebook's Open Graph, a tool for developers to hook their apps directly into Facebook, allows for far better display of those photos.

There's a good reason for Armbrust and colleague to highlight independent app developers.

Facebook is in the middle of trying to buy Instagram, in a cash-and-stock deal that was worth $1 billion at the time it was announced. The Federal Trade Commission is investigating the deal to see if it violates antitrust law.

Naturally, Facebook wants to avoid antitrust scrutiny. Bragging about the number of photos people share on Facebook isn't a great move—unless Facebook also takes pains to point out how open it is to independent developers.

Update: We've updated this post to note that Facebook had previously announced the figure of 300 million photos a day.