Comcast will be pulling the plug on Usenet newsgroups on October 25, and will now no longer offer its availability to new subscribers.

From www.comcast.net/newsgroups:
The Comcast Newsgroups service (powered by GigaNews) has been discontinued.
We apologize for any inconvenience.
If you have already signed up for Comcast Newsgroups, please be aware that this service will be discontinued on 10/25/2008

There are many Usenet providers, free and paid, available for those who want to continue using this long-lived internet service. In some areas, those who have expressed their displeasure to Comcast sales dept. about this have been offered a few months of internet service with $5/mo discounted.

Usenet is one of the oldest services on the internet, probably just behind email and ftp. Web-based and mail lists have assumed much of the load of providing discussion forums, but Usenet groups have always provided an organized and easily accessed platform for thousands of topics.
My earliest internet use in the early 1990's was accessing computer and radio hobby newsgroups via the MSU Gopher server, using the old MichNet free(!) dialups.

RoadRunner/BrightHouse dropped their own usenet service a couple of months ago but farmed it out to one of the 3rd party outfits. I'm betting that they will follow Comcast sometime next year.

Other ISPs have dropped it 0ver the past few months. It is partially economic, with a shrinking percentage of ISP subscribers using (or even aware of) Usenet. Also, the NY State Attorney General has gone after ISPs in that state, demanding they deny Usenet to all, claiming that the "binary" groups harbor and provide relatively anonymous access to pornographic material, notably of the child variety. Rather than filter out those groups, ISPs nationwide are simply killing off Usenet altogether as a subscriber service.