Just over a month has passed since Tumblr introduced sponsored posts on mobile, its first ad unit that looks and feels like a regular post. Starting today, visitors will also begin to see sponsored content on desktop.

Previously, Tumblr’s ads limited advertisers to the “Radar” post that appears on members dashboards and alternated between paid promotions and spotlight placements. Sponsored posts mark the first ad unit to live in-stream.

Similar to Tumblr’s mobile ads, visitors will only see up to four sponsored posts per day, and each post will be marked by an animated dollar sign. Viewers will be able to reblog, like, follow, and share these ads directly from their web dashboard.

Tumblr’s first web ads will debut with seven pilot partners, including Viacom, Ford Motor Company, Universal Pictures, Capital One, AT&T, Denny’s, and Purina. According to Tumblr, sponsored posts have already seen over 10 million likes and reblogs since their launch in April.

“The engagement rates on the Tumblr Radar and Sponsored Mobile Posts have been spectacular and we have taken this same carefully architected approach to this new web in-dash opportunity,” explained Lee Brown, global head of sales at Tumblr. “The Tumblr post is a flexible, dynamic and expressive medium, and we are delighted to give marketers yet another opportunity to promote their content and connect with this vibrant and engaged community.”

It’ll be interesting to see how the ad unit fares over time. It’s still a relatively new addition to the platform, and much of Tumblr’s user base is still reeling from the Yahoo acquisition. Introducing new ads might cause more members to leave in favor of other blogging platforms. Hopefully the company releases more engagement data in the coming months.

[Via: TechCrunch, Image credit: Sasha D Butler]