The 1/8000 shutter speed was actually first introduced on 35mm film SLRs back in the 1980s. I believe the Nikon N8008 was the first. My old Nikon F4s film camera has 1/8000 top shutter speed, as does my digital Canon 5DmkII. As to its usefulness, I have used it exactly once, with the F4s, when I was in high school in 1994, when photographing a sports event for the school newspaper. It would be most useful for sports and wildlife work, and even there it would be used rarely.