Portland, Ore., will get Comcast-branded WiMax courtesy of Clearwire's network: The cable companies have had increasingly strong ties with Sprint Nextel over the years in order to deliver a quadruple play (video, voice, data via coax plus wireless via Sprint). Comcast and others invested heavily in the new Clearwire; Comcast's share so far is $1b. Comcast's data speeds aren't challenged by what Clearwire has, but Comcast can't offer mobile high-speed data, especially with national roaming, and that's what Clearwire + Sprint can do.
The Oregonian reports that Comcast's COO made the announcement in a Portland visit this morning. Comcast will likely offer a multiple-play bundle. For Clearwire it's a win, even though it'll only get a wholesale price for service Comcast sells, because the company doesn't have to spend the money marketing and retaining the customer, nor presenting a bill to the household, nor dealing with collections. Further, Clearwire benefits by every additional customer in spreading out its overhead, even if it only recoups cost plus a bit off the wholesale price.
Comcast is testing some limited Wi-Fi in the Northeast in conjunction with Cablevision, which has is spending $300m to bring Wi-Fi to its tri-state customers with cable broadband subscriptions.