Breaking: TVNewser has learned that all three evening news anchors, CBS’ Katie Couric, ABC’s Charles Gibson and NBC’s Brian Williams will appear live, in studio, on all three network morning shows tomorrow morning. The appearances will be to announce a cancer-research telethon airing on ABC, CBS and NBC on September 5.

All three network anchors will appear together on all three morning shows, as they travel around New York City to make the appearances. “It is logistically possible,” says our source.

Earlier this morning, TVNewser reported that Matt Lauer announced Couric’s, “major announcement,” in a tease on the Today show this morning.

> Update: ABCNews.com’s Emily Friedman explains further: “‘Stand Up To Cancer,’ will air on Sept. 5 on ABC, CBS and NBC and will feature live performances by recording artists and movie and film stars who will, along with the evening news anchors from each of the networks, deliver information about potentially life-saving cancer research.”