Skype on the PSP wasn't exactly a secret, but here are the details on the functionality (pretty much the same as Skype on a PC, without IM). You also need a Memory Stick Duo and headset. More here:

New PSP(R) (PlayStation(R)Portable) Expands Its Entertainment Experience by
Introducing Skype(TM)

TOKYO, Jan. 6 /PRNewswire/ — Sony Computer Entertainment Inc. (SCEI)
today announced that it would introduce Skype(TM) features to the new slim and
light PSP(R) (PlayStation(R)Portable) handheld entertainment system (PSP-2000
series). More than 246 million members are registered for the use of this
communications software, which enables users to communicate with other Skype
users around the world over the Internet. Calls between Skype users are free
of charge.
(Logo: http://www.newscom.com/cgi-bin/prnh/20020701/SFM066LOGO )
By introducing Skype on PSP, the following features and services will be
made available to PSP users (*1) (*2):

— Free voice calls between Skype users
— Skype contact list management (view existing contacts, add new ones)
— Skype presence (see which friends are online and available to talk)
— SkypeOut(TM) calls to make calls to landlines and mobile phones
anywhere in the world (requires the purchase of Skype credit)
— Optional SkypeIn(TM) number that lets users receive calls on Skype from
landlines and mobiles anywhere in the world (requires the purchase of
Skype credit)
— View and modify Skype settings and account details (including username
creation, SkypeOut settings, voicemail settings and call forwarding)

PSP users worldwide will be able to start using Skype features and
services through a simple system software update scheduled in late January.
After updating the PSP system software, a Skype icon will be added to the
Network category in the home menu. PSP users who do not yet have a Skype
username can register by clicking the icon and following the instructions.
PSP users who already have a Skype username can immediately sign in by
clicking the Skype icon and entering their username and password.
SCEI will deploy various measures to meet users' demand and vigorously
promote the expansion of the PSP platform as a handheld entertainment system
to enjoy a variety of interactive digital entertainment.

* For more information on Skype, please visit www.skype.com

(*1) To enjoy Skype features on PSP, users will need Memory Stick Duo(TM),
a wireless Internet connection and a Skype-compatible audio input
device.
(*2) In order to receive calls, users must be connected to the Internet
and signed in through the Skype screen on PSP.

About Sony Computer Entertainment Inc.
Recognized as the global leader and company responsible for the
progression of consumer-based computer entertainment, Sony Computer
Entertainment Inc. (SCEI) manufacturers, distributes and markets the
PlayStation(R) game console, the PlayStation(R)2 computer entertainment
system, the PSP(R) (PlayStation(R)Portable) handheld entertainment system and
the PLAYSTATION(R)3 (PS3(R)) system. PlayStation has revolutionized home
entertainment by introducing advanced 3D graphic processing, and PlayStation 2
further enhances the PlayStation legacy as the core of home networked
entertainment. PSP is a new handheld entertainment system that allows users
to enjoy 3D games, with high-quality full-motion video, and high-fidelity
stereo audio. PS3 is an advanced computer system, incorporating the state-of-
the-art Cell processor with super computer like power. SCEI, along with its
subsidiary divisions Sony Computer Entertainment America Inc., Sony Computer
Entertainment Europe Ltd., and Sony Computer Entertainment Korea Inc.
develops, publishes, markets and distributes software, and manages the third
party licensing programs for these platforms in the respective markets
worldwide. Headquartered in Tokyo, Japan, Sony Computer Entertainment Inc. is
an independent business unit of the Sony Group.

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