The Twitter brain trust has decided to turn some of their exponentially-growing traffic into a monetary outlet with the upcoming launch of their self-serve ad platform.

Following the Facebook promotion method, Twitter’s ad service will, according to MediaPost.com, allow Twitter users to create two types of self-serving advertisements:

Promoted Tweets and Promoted Accounts.

The Promoted Tweet aspect encourages followers to interact with the message in question, in the form of re-tweeting and other methods.  As for promoted accounts, this campaign will attempt to get more followers for the Twitter user doing the promotion — essentially, it’s a “hey, follow me” blast — whose appearance across the Twitter network depends on which user recommends it.

Image courtesy of MediaPost

The appearance of the Promoted Account in a tweet stream depends a great deal on what keywords the user targeted, as well as the Twitter users the account in question is following.  Once a Promoted Account tweet is recommended, Twitter will display it to relevant users — again, based on keywords and followers.

The user will then be charged for any followers they pick up.  As far as cost, MediaPost has more:

As far as Promoted Tweets, users must select from a recently-tweeted message.  Once promoted, these tweets will appear in Twitter streams of those following the account, and will be annotated as such.  They will also appear to users who follow accounts similar to the one doing the promotion.

For instance, if you’re promoting a tweet from an SEO blog, chances are, your tweet will appear to users who follow the Danny Sullivans of the world.  All promoted tweets and accounts will be labeled as such, “Promoted by _____,” which should eliminate any confusion.