Chicago-area residents have been teased by Sprint and Clearwire since the companies gave a sneak peak of their Mobile WiMax technology back in 2007, giving boat-riding journalists an early look via temporary downtown tower array. Sprint subsequently promised a Chicago launch in 2008, but despite an unofficially lit network, it never became fully commercially available -- until now. Sprint is circulating an e-mail announcing that they're launching Mobile WiMax in the city on October 6 as part of a full day launch event:Mmm, you can already "feel the now" with Sprint executives, hors d'oeuvres, cocktails and Mobile WiMax. Comcast, which has been busy reselling Clearwire service, had already hinted at launches in both Chicago and Philadelphia. Clearwire promises to launch the service in 80 markets within 18 months, though as we explored yesterday, there's some early connectivity headaches they'll need to address moving forward. A major market like Chicago is going to be a big test for the new operator.