Charles Gibson by Ina Mae Astute/ABC, Brian Williams courtesy NBC and Katie Couric by Andrew Eccles/CBS Charles Gibson by Ina Mae Astute/ABC, Brian Williams courtesy NBC and Katie Couric by Andrew Eccles/CBS

The "big three" networks are putting ratings wars aside for at least one day in September when ABC, NBC and CBS will each "Stand Up to Cancer" by airing a fund-raiser to benefit research.

Each of the nets will donate one hour of commercial-free, primetime coverage to the telethon simultaneously, says Variety. Each of the networks' evening news anchors - Charles Gibson, Brian Williams and Katie Couric (whose husband died of colon cancer in 1998) - made the rounds on each network's morning shows today to promote the telethon, on which they will all appear as well.

The fund-raiser will air Sept. 5 and will feature live performances from music artists as well as appearances from film and TV stars, none of which have been announced at this time. - Adam Bryant