This book is edited by Martin, although he has one story in it. This is the book to read prior to reading any of the other Wild Card books. This details how and what made the Wild Cards.
An alien virus genetically alters a percentage of Earth's population. The results are grotesque disfigurement for some and enormously enhanced abilities for others. The people with enhanced telekinesis, invisibility and other enhanced abilities while maintaining a reasonably normal body are called Aces. The deformed, the grotesque, the severely impaired are called Jokers.
This book is a compilation of short stories detailing who released and created the virus and the initial results of that release.
As in all collections of short stories, there will be some you love and others you wonder how did they get in with such exalted company.
web site: http://www.tor.com/features/series/wild-cards
This book may have been received free of charge from a publisher or a publicist. That will NEVER have a bearing on my recommendations.