A person who is a nobody in real life but is somehow "popular" among cyber geeks and internet communities. The person will often have "followers" and "friends" whom they've never met but who hang on their every post and send them messages of admiration on a regular basis.
"What are you doing on your iphone now?"
"Posting on my blog, can't you see I'm a cyberlebrity? My fans want to know what I'm doing now."