Twitter's self-service advertising platform launched in December last year, allowing around 100 big-name accounts to post promoted tweets to the microblogging service. Today, this number has been expanded by 100 times, with 10,000 accounts now eligible to create the adverts. The selection of which accounts the service is open to isn't arbitrary, though: the wider rollout is in itself a sponsorship deal with American Express, and the selected accounts either use or accept AmEx for payments. New advertisers will also receive $100 advertising credit to begin their campaign.

Whether the advertising platform is a success for Twitter won't be revealed until the company decides to announce numbers on the project. However, if promoted tweets become increasingly prevalent, it has to be questioned whether users will become disenfranchised with the service as the balance between the people they follow and paid tweets shifts. The move comes as more business accounts adopt brand pages, another way for companies to differentiate between their accounts and regular users.