A reliable source at Comcast has provided me with the March launch schedule for the company's speed increases that have been slowly deploying nationwide. As noted last month, Comcast's Blast tier is going from 25/4 Mbps to 50/10 Mbps, their Extreme tier will be going from 50/10 Mbps to 105/20, and their Performance tier will be going from 12/2 Mbps to 25/4 Mbps for all users.

Many customers on the East Coast and scattered other cherry picked regions across the country have been enjoying these increased speeds for some time, but now a source has provided some additional solid detail for those of you waiting for the upgrade. According to the source these are the loose launch dates:

•Most Chicago users should have started seeing the speeds as of yesterday.

•Michigan, Indiana, Kentucky customers who weren't pat of earlier, selective deployments should start seeing the speeds tomorrow, March 6.

•South Florida should start seeing the speeds on March 21.

•Georgia and North Florida should start seeing the speed increases on March 27.

Note that with the shift to faster speeds, Comcast has been getting rid of PowerBoost, which used to provide a brief additional burst of speed at the beginning of a download. With speeds getting so fast outright, PowerBoost has, at least on the downstream side, become irrelevant.

Many of these markets will be seeing Comcast's 300 Mbps tier, though according to the source the tier is more about bragging rights than anything else -- and isn't heavily marketed to consumers. Many of these same markets won't be seeing the Performance tier boost from 12/2 Mbps to 25/4 Mbps until April or May.