If you begin to receive Tweets from friends that seem contrived, or maybe a bit too much like a sales pitch, it might be because those friends have been recruited into Magpie - an ad network created for Twitter.
As we all await the big idea on how Twitter will finally generate ongoing revenue, Magpie is certainly attempting to demonstrate proof of concept - a pilot, if anything, to test the waters. The model is simple - get avid Twitterers, presumably with lots of followers, to allow advertisers to embed their own messages into their Tweets from time to time. It's important to note, that Magpie is not affiliated with Twitter - it is a separate entity, leveraging the Twitter platform as an advertising arena.
While Twitterers won't be able to review and approve ads that are sent out from their Twitter account in advance, Magpie does allow members to tag each ad with their own disclaimer - written by the member to distinguish genuine Tweets from Magpie ads. And there is money to be made! Magpie offers four different models to their members: Pay-per-Sale, Pay-per-Lead, Pay-per-Click, and Pay-per-View.
The question remains, if users don't tag their Magpie ads with a clear customized message, how many of us will mistake a brand message for an honest Tweet? And if we do, does it matter? As Magpie picks up steam, there's a chance ad Tweets could outnumber those from our friends. Here's hoping we all still find true value in the person to person exchange, and that the organic discussions Twitter seems to facilitate won't be disrupted by the Magpie model.
For more information on how Magpie works, visit their FAQ page.