I'm sure there are plenty of people that don't know who Janis Joplin is (i mean, a load of people in my school had never heard of Woodstock. Which i thought was practically impossible) but i think anyone with an interest in music would know who she is.
She was an amazing talent as well. One of those voices that.... if you hear a song by her that you've never heard before in your life, you'll instantly recognise her as the person singing it. Very unique talent.