Guys, look what I found this morning. There were some speculations about Vertcoin's instamine, but the article I found explains perfectly how it was done and how big was the instamine.
I have a link on my other PC, so if anybody's interested I'll find and post it later.
My respects to the author, he/she did amazing job researching this.
Wow! I've read somewhere that Vertcoin might had a hidden instamine... but this is a real research and it definitely proves there was instamine! :-/