Actually, theres some limitations.
First off, they already offer a 6 mbit / 768 kbit tier. This costs $10 extra a month
They are going to upgrade thier tiers ONLY for cable subscribers. So if you are an internet subscriber and NOT a cable customer you dont get the upgrade (this would be me...)
Basically it is 4 to 6 mbit (no change in upload) for the cable subscribers without the speed upgrade. and 6 to 8 mbit for the cable subscribers with the speed upgrade.
Although you can upgrade to the 6 mbit one for $10 more and the 8 mbit one fro $20 more a month.
Should be up later this summer.