Comcast did a speed upgrade on their network today. If you had Blast then you will now 105mbps, if you had Extreme 105 you will now have 150mbps. There have been reports of the lower tiers getting bumped to 50mbps. You will need to restart your cable modem to get these speeds. Also, keep in mind you will need a 16-channel bond DOCSIS 3 modem to get 150mbps if your on extreme. You can rent one or buy one for about $90. A DOCSIS 3 modem is also required for 50mbps.
Upload speed remains the same on all packages. They should really change this.
There is some unconfirmed talk about 150mbps being switched to 305mbps.
Update: It seems a very limited number of people have gotten this. As far as I know it's only confirmed in the Northeast. If you're in the Northeast and had success let us know.