Mr. Karp's Tumblr avatar (mashable.com)

Apparently Tumblr CEO David Karp has overcome his distaste for ads, because he just announced that advertisers will be able to buy access to the dashboard's "Tumblr Radar."

About 45 minutes ago, Rex Sorgatz tweeted the following dispatch from AdAge Digital: "Karp just announced that the Featured spot on the Tumblr dashboard is going up for sale to advertisers." Business Insider is reporting that the feature will go live as early as May 2.

Reached via email, Mr. Sorgatz provided more detail, telling Betabeat:

"It was the strangest 'closing keynote' speech I've ever seen. He was scheduled to talk for a half hour, but I think the whole thing lasted 7 minutes. He cited some growth numbers, mentioned how much he appreciates the creativity within the advertising community, and then broke the news that Tumblr would be opening up that spot to advertisers."

Mr. Sorgatz continued: "He gave no specifics, other than that it launches May 2. He flashed his email address on the screens, took no questions, and then zipped out the building."

Tumblr spokesperson Katherine Barna also told Business Insider that this new feature  is "not an 'ad unit' per se, but a package of native promotion for the Tumblr post ― the most essential and versatile piece of our network." We've reached out for clarification and will update as we soon as we learn more.

Regarding his earlier opposition to ads, Business Insider provides the following recantation from Mr. Karp: "I was probably being an idiot then." He also informed the audience that 122,302 users signed up for the service yesterday alone. Just last week, Mr. Karp told AdAge that Tumblr could toss up Google AdSense and be profitable almost immediately, but called it "a complete last resort."

At the time we took Mr. Karp's comments to mean no ads at all, but apparently after five years and $125 million in venture capital, Tumblr now finds itself last resort-adjacent, to use Mr. Karp's parlance. After some half-hearted attempts, it looks like the time to monetize is finally nigh and advertising will be the way.