Comcast this morning stated that the nation's soon to be largest broadband operator would be deploying their new "Extreme 50" 50Mbps DOCSIS 3.0 tier in parts of Baltimore, Chicago, Atlanta, and Fort Wayne, Indiana. Comcast says that initial deployment will cover only some of these cities this month, with the remainder of those markets getting finished up in early 2009. Comcast spokesman Charlie Douglas tells me that with these launches, they've now completed their goal of upgrading 20% of their markets with DOCSIS 3.0 by the end of 2008.

50Mbps arrived in the Twin Cities last April, with Metro Boston, Philly Metro, Northern New England and Southern Massachusetts markets arriving in October. November saw launches in Seattle, Portland, Spokane, and Eugene.

In upgraded markets, Comcast is not only upgrading existing speed tiers ($42.95 "Performance" 6Mbps/1Mbps and $52.95 "Performance Plus" 8Mbps/2Mbps tiers became 12Mbps/2Mbps and 16Mbps/2Mbps), but is adding two new tiers to the mix ($62.95 "Ultra" 22Mbps/5Mbps and the aforementioned $139.95 "Extreme 50" 50Mbps/10Mbps).

One recurring theme we've seen in our forums is that the new speeds have many users downgrading. In both forum threads and polls, many customers on Comcast's 16Mbps/2Mbps tier say they're downgrading to their 12Mbps/2Mbps tier -- apparently because they don't think an additional 4Mbps downstream is worth $10. Customers used to be willing to pay the additional $10 for double the upstream speed, but there's no longer an upstream difference between the tiers.

Meanwhile, $139.95 for broadband remains a little too rich for most people's blood. The less expensive 22Mbps, $62.95 tier seems more popular among speed freaks. As always, curious users can track deployments and customer experiences in our Comcast forum.