Spelljammer: Shadow of the Spider Moon is a Polyhedron d20 Mini-Game bundled with Polyhedron 151/Dungeon 92.
The d20 SJ issue of Polyhedron will have the following content:
The core races and classes, plus the following Prestige Classes: Master Scavenger, Planetary Explorer, Spelljammer Ace, Stellar Corsair, Storykeeper; new skills and feats appropriate to the setting.
New feats include: Acrobatic, Atheletic, Ballista Master, Ballista Specialist, Born Spacer [Background], Cannon Master, Cannon Specialist, Craft Spelljammer Helm, Education [Background], Endurance, From the Gutter [Background], Mysterious Heritage [Background], No Identity [Background], Noble Birth [Background], Spelljammer Helm Operation, Spelljammer Specialization, Stealthy
Spelljamming helms, Movement, Ship Combat and Maneuvering, Ship descriptions (and illustrations).
Ships include: Tradesman (human), Hammership (human), Archelon (human), Warbird (elf), Arrowing (elf), Armada (elf), Wreckship (gnome), Spinneret (drow), Deathspider (drow), Great Mother (drow), Boreworm (illithid), Nautiloid (illithid), Dreadnaught (illithid)
Ships will have the following special ship attacks: Webshot, Spelljammer Grappling
Spelljammer equipment including firearms and ship-weaponry.
New equipment includes: Ballista, Cannon, Cutlass & Small Cutlass, Flamegun, Pistol, Rifle, Scattergun, Spittergun
New magic items include: Floatanchor, Gabadout, Lifejammer Helm, Spelljammer Helm
The Crown of the Stars will also be included as an artifact.
The Spelljammer setting.
Mind Flayers, Drow, Yuan-Ti, Formians, and Sahuagin.
In addition, there will be cardboard counters of a whole bunch of Spelljamming ships.