Jackpoint is an distributed peer-to-peer (p2p) network created by the legendary decker Fastjack and limited to several dozen hand-picked members. It serves as the fictional narrative within which Shadowrun Fourth Edition supplements are presented, the same way Shadowland was used before.
Outside of the in-character context, Jackpoint is the fictional format used to present the fictional, in-character contents of the sourcebooks and other supplements in Shadowrun Fourth Edition. It was designed, in part, to create a smaller stable of regular characters that could be used to develop an overarching storyline among them, and also to reduce the complexity and possible inconsistencies that arose with having over 15 years worth of shadowtalk posters appearing in the books. It also eliminated the problem of numerous one-shot posters who appeared in single books and never appeared again. At least when it occurs in SR4 supplements, it is given an in-character reason why Lei Kung, et al. appear (They are recognized as the top experts on shadowrunning in Hong Kong) in Runner Havens. But even in that case, Lei, et al. were relatively well-known before SR4 due to their knowledge on Hong Kong and Wuxing, particularly.
Jackpoint is an encrypted, distributed peer-to-peer (p2p) network created by the legendary decker Fastjack following the Matrix Crash 2.0 of 2064 which destroyed the Shadowland darknet. The network has no centralized server, but exists within the commlinks of its approximately sixty users--all of whom have been selected by Fastjack for various reasons which include having access to valuable information to the rest of Jackpoint's members and the willingness to share (some of) it. The members represent a wide variety of backgrounds and interests, and operate throughout the world. While the network was designed for full members selected by Fastjack, other individuals possessing unique and/or detailed information of interest to the network can be invited to post files, and entries in larger files. They also have limited read/write access to annotate specific files with "shadowtalk" comments.
The Jackpoint software suite contains several programs for private and collaborative messaging, a reputation system, integration with the user's e-mail, and Matrix feeds (e.g., news; personal alerts), as well as a file storage area and management. It also contains the software that allows the network to operate from even one member's commlink.
Along with the above-mentioned members, Jane Foster ("Frosty") is a member. So are several historically well-known Shadowland users from the 2050s and 2060s such as the decker, Smiling Bandit; the shaman, Man-of-Many-Names, the sociopathic runner/pirate, Kane; the mercenary, Picador; and the ex-ganger turned assassin, Riser. The most notorious member (Kane notwithstanding) both among Shadowrun players and Jackpoint users is the Deus-following Otaku, Puck.
There is a certain amount of controversy inherent to, and building (and will continue so long as the Jackpoint format remains standard), among these few dozen individuals. One instance is the inclusion of Puck as a member of Jackpoint. Several members such as Slamm-O! hold him in suspicion or outright contempt for his former association with the AI Deus during the shutdown of the SCIRE from December 2059 to May 2061. Puck was one of the leaders of the "Whites"--Otaku loyal to Deus. His standing within the Jackpoint reputation system is perpetually at the very bottom.
Another controversy exists involving two members: Netcat and Clockwork. During the events of 2070 that announced to the world the existence of Technomancers and AIs within the Matrix, it was revealed that Netcat was a technomancer. Clockwork reacted harshly, condemning Netcat as insane, and an abomination--in spite of his own background of persecution for being a hobgoblin (a Middle Eastern ork metavariant). This eventually led to a situation where Clockwork "outed" Netcat to NeoNET, whose operative failed in an attempt to capture her. While this led to widespread condemnation among the members, because it did not involve infractions of the rules for using Jackpoint Fastjack refused to kick Clockwork out of the network.