Dive Brief: 

• Tumblr users may notice a Starbuck cup in place of the period in the logo today: It's an ad.
• The period is now for sale to advertisers as the Sponsored Tumblr Dot. 
• The ad isn't available everyday, but Starbucks has purchased the very first Sponsored Tumblr Dot to capitalize on National Coffee Day. 

Dive Insight: 

Selling part of a logo is new territory for digital ads. It's unlikely that Sponsored Tumblr Dot will be highly effective for either Tumblr or Starbucks, but it would be interesting to see the numbers. It will also be interesting to see the reaction from diehard Tumblr users, as they were notoriously unhappy when Yahoo acquired the social site.