Launching in February is a new attempt at monetizing Twitter, not by Twitter themselves however, but an advertising network called The Branch.
Founded by Zerk Media with founder James Avery, The Branch aims to create an advertising network from the various twitter tools and applications out there and, with a bit of work, this just might work. Zerk Media appear to have had experience in the ad network game with other networks such as The Lounge, a Microsoft Developers focused network and Ruby Row, focused on Ruby Developers.
With over 400 Twitter services out there working off the Twitter API, the majority advertising supported, it makes sense for one entity to manage the advertising between them. From the look of things they will need some time to confirm partnerships but with twitpic and twitter gallery on board already, it’s a good start.
There have been other attempts at creating an ad-network from Twitter; Twitter themselves has made attempts to integrate advertising in their Japanese service and there is of course the notorious Magpie ad network which attempts to pay people to integrate advertising into their tweets.
The current rates are $2200 a month with a discount of $200 if you are willing to enter a 3 month contract.