Twitter's first attempt at monetization is called 'promoted Tweets'.
Paid trends that usually appear in the top ten with a defining label.
It started with the Twitter home page (both new and old versions) and the popular Twitter client Hootsuite.
It appears the Adobe Air version of Tweetdeck has joined the fray this morning, automatically turning on Worldwide Trends for some users including promoted Tweets.
A screenshot from earlier this morning appears below.