According to an article posted in Detroit News (originally in Washington Post) , DirecTV satellite subscribers will be able to tune in several XM Satellite Radio channels free beginning in November. Read more...

Dish Network offers its customers Sirius. It is available only to customers who buy the more expensive programming package. It offers 65 channels.

Source: http://www.detnews.com/2005/technology/0510/01/0tech-332431.htm