JAPAN (76 companies)

• ACQUIRE Corp.
• ALPHA･UNIT CO.,LTD
• ALVION Inc.
• AQ INTERACTIVE INC.
• AQUAPLUS Co.,Ltd
• ARC SYSTEM WORKS Co.,Ltd.
• ARIKA CO.,LTD.
• ARTDINK CORPORATION
• ASCII MEDIA WORKS Inc.
• ASGARD Co.,Ltd.
• Aspect Co.,Ltd.
• BROCCOLI Co.,Ltd.
• Capcom Co., Ltd．
• CHUN SOFT CO., Ltd
• Codemasters Software Company Limited
• Crafts & Meister Co.,Ltd.
• CyberConnect2 Co.,Ltd.
• CYBERFRONT Corporation
• D3 PUBLISHER Inc.
• DIGITAL WORKS ENTERTAINMENT INC.
• Dimps Corporation
• dorasu corporation
• Edia Co., Ltd.
• ENTERBRAIN, INC.
• FromSoftware, Inc.
• Gameloft K.K.
• GANBARION Co.,Ltd.
• Genki Co.,Ltd.
• Grasshopper Manufacture Inc.
• GungHo Online Entertainment,Inc.
• GUST CO.,LTD.
• HAMSTER Corporation
• HUNEX CO., LTD.
• IDEA FACTORY CO., LTD.
• Ignition Entertainment Ltd.
• IMAGICA DIGITALSCAPE Co.,Ltd.
• Index Corporation （Atlus）
• IREM SOFTWARE ENGINEERING INC.
• Jorudan Co.,Ltd.
• KADOKAWA GAMES,LTD.
• Kadokawa Shoten Publishing Co., Ltd.
• KAGA CREATE CO., LTD
• Konami Digital Entertainment Co., Ltd.
• LEVEL-5 Inc.
• MAGES．Inc (5pb)
• Mainichi Communications Inc.
• Marvelous Entertainment Inc.
• media5 Corporation
• NAMCO BANDAI Games Inc.
• Nihon Falcom Corporation
• Nippon Ichi Software, Inc.
• NOWPRODUCTION, CO.,LTD
• OaKs co., Ltd
• PAON CORPORATION
• POLYGON MAGIC, INC.
• PROTOTYPE CO.,LTD.
• Q Entertainment Inc.
• SAFARI GAMES., Ltd
• SEGA CORPORATION
• SilverStarJapan Co., Ltd.
• SNK PLAYMORE CORPORATION
• Sonic Powered co.,Ltd.
• Spike Co.,Ltd
• SQUARE ENIX Co., Ltd.
• Starfish-SD Inc.
• SUNCORPORATION
• SystemPrisma Co.,Ltd.
• SystemSoft Alpha Corp.
• TECMO KOEI GAMES CO., LTD.
• TGL
• TOMY Company,Ltd.
• TOSE CO., LTD.
• tri-Ace Inc.
• Ubisoft K.K.
• Views Co.,Ltd.
• YUKE'S Co., Ltd.

NORTH AMERICA (20 companies)

• Activision, Inc.
• Capybara Games
• “CCP”
• Demiurge Studios
• Electronic Arts
• Epic Games Inc.
• Far Sight Studios
• Frima
• High Voltage Software
• Kung Fu Factory
• Paramount Digital Entertainment
• PopCap Games
• Powerhead Games
• Rockster Games
• THQ
• Trendy Entertainment
• Ubisoft
• Warner Bros. Interactive Entertainment
• 2K Games
• 2K Sports

EUROPE/PAL (57 companies)

• Alawar
• Allegorithmic, makers of Substance
• Beatnik Games
• Beatshpers
• Blitz Games Studios
• Broadsword Publishing Limited
• Catalyst Outsourcing
• “CCP”
• Climax Studios Ltd
• Codemasters
• Codeplay
• Electronic Arts
• Enigma Software Productions, SL
• Eurocom Entertainment Software
• Eutechnyx Ltd
• Exient
• Firelight Tech
• Fresh3D
• FUN labs
• Gameloft SA
• Gameshastra
• Home Entertainment Suppliers PTY Ltd
• Honeyslug
• Icon Games
• Impromptu Software Ltd
• Just Add Water Ltd
• Kuju Doublesix
• Lexis Numérique
• Mobile Interactive Group Ltd
• Namco Bandai
• NaturalMotion
• Playerthree Ltd
• Rebellion
• Rockstar Games
• Rubicon Mobile
• Sanuk Games
• SEGA
• Sidhe Interactive
• Spinvector
• Stainless Games Ltd
• StormBASIC Games
• Sumo Digital Ltd
• Tag Games
• Take2
• The Game Atelier
• THQ
• Tonika Games
• Trine Entertainment Ltd
• Trinigy
• Tru Blu Games
• Ubisoft Entertainment SA
• Umbra
• VeeMee
• ZAPPAR
• Zen Studios Ltd
• 2K
• 505 Games

http://www.andriasang.com/e/blog/2011/06/07/vita_third_party/

AWESOME!

Now let's put some titles for those developers. C'mon Sony, I want a few PSP titles, and the 3DS has been a snoozefest so far: strike while you can, and convince me to buy your system!

Updated the OP. Joystiq actually had it incomplete!
total is over 150 now!

D3 = EDF. I just know it!

IF true and IF they localize it I will def buy it!

Over 150 developers working on the system...