Yes, it's used for someone who always does something to get attention, or loves attention. This can include show-offs, but also drama queens. Obviously from the word "whore", it's a negative thing to say about someone.
From various blogs:
"Bodybuilding is full of attention whores. You will fit right in. Just Sayin'."
"SELFIES: Do they prove you are an insecure narcissistic attention whore begging for 'look at me' validation?"
"And this attention whore... just wants to be famous because he's a sh*tty lawyer and nobody will hire him..."