Instagram turns three this week. Hard to imagine the world without the latest candid camera celeb close-up available on their official feed. The social media magnet celebrated a few milestones in year three, as reported on their blog: more than 150 million people use the service each month (up 50 million since February), they added video and the first InstaMeet mustered in Russia.

The company says, “We’re humbled and excited to watch the Instagram community continue to grow and thrive.” And with the goal of becoming a sustainable venture, Instagram announced this week that some ads may infiltrate US-based user feeds. The team promises users the ability to hide ads they dislike and a forum for feedback. Early photos and videos will be from brands already using the social media tool.

TrackMaven, a competitive analysis firm, conducted a study on just how exactly Fortune 500 companies are using Instagram to promote their brands. The study found that 123 of the elite brands have Instagram accounts, 91 percent of those have a minimum of one post, 85 of the 123 had posted within the 30 days preceding the study. Of the brands using the social media tool, Nike has the most followers (just over 2 million), Foot Locker has posted the most photos (1,018) and Target the most videos (that’s 39). Nordstrom is the only one of the companies to place in the top ten of followers, photos and videos.

Facebook saw the writing on the wall, purchasing the little app that could in 2012 for double its valuation at the time. And it seems Instagram has pop culture approval. E! Online ranks Instagram as #30 in its The 100 Best Things in Pop Culture! awards.

US government entities such as the White House, NASA and the Department of the Interior are on-board and posting, too. The Department of State celebrated its first Instagram in September, Secretary John Kerry proclaiming, “Finally, the State Department is on Instagram… and we hope you’ll follow us around the world.”

And to top off the global recognition of Instagram’s anniversary, well-wishers can celebrate with an Instagram cake (shown above) that was featured on How To Cook That, a blog hosted by home cook, food scientist and dietitian Ann Reardon.

[Images via Instagram, Nordstrom Instagram, NASA Instagram, How To Cook That blog.]