interestingly enough, I've got a few links & numbers of my own, according to the same source of information:
http://en.wikipedia.org/wiki/Microsoft_Game_Studios
http://en.wikipedia.org/wiki/Nintendo
http://en.wikipedia.org/wiki/Sony_Computer_Entertainment#Software_development_studios
Overall, Sony has 15 first party devs, 19 second party devs, Nintendo has 18 first party devs, 19 second party devs, MS has 10 first party devs, no second party dev, and 12 "affiliate" 3rd party devs (technically 11 since Bungie is already with Activision).
Out of Sony's 15 first party devs, other than Forster City Studio (they only oversee and co develop Sony games with other studios), all of them have their own unique IPs, only 2 of them have 1 IP (GG and Media Molecue), all others have 2 or more unique IPs on their development records. So far 5 New PS3 IPs have been created/close to finish by first party devs (ignoring PSN titles and PS Home; eyepet is ignored because its eyetoy based, which is last gen; co - developments with studios outside Sony are also ignored):
Uncharted, Mag, Last Guardian, Motor Storm, LittleBigPlanet.
Out of Nintendo's 18 first party devs, 5 of them have worked on Mario or Mario related games, 3 of them worked on Donkey Kong or DK related games. they developed 7 new IPs for Wii so far (ignoring WiiWare titles, SMG is also ignored because of Mario factor):
Wii Fit (plus), Wii Party, Wii Sports (resort), Wii Play, Wii Music, Xenoblade (JP only), Disaster: Day of Crisis.
Out of MS' 10 first party devs, 1 is for Windows Phone 7, 3 of them only developed 1 "Kinetic" title each, 3 are new studios with no games (343 for new halo, Firebird for an unannounced game, Wingnut Interactive partners with Peter Jackson for a "filmic game"), so far 5 new IPs have been created for Xbox 360 by first party devs (ignoring XBL titles):
Kinetic Joy Ride, Kinetic Adventures, Kinetic Sports, Viva Pinata, Kameo: elements of Power.
Now, is it really that hard to see the quality and variety of Sony's new IPs compare to MS/Nintendo? They push their devs for something new and they support a big range of games, if you want to add 3rd parties to MS' case (Gears of War, Alan Wake, L4D ect ect), don't forget Sony still has plenty of 2nd parties (inFamous, Heavy Rain, Resistance ect ect) and co - developments (ModNation Racers, Sports Champion ect ect). 3rd parties (Demon's Souls, Agent, Heavenly Sword ect ect) are not even included in the discussion since we're talking about Sony's Variey here.
Edit: Removed Warhawk from Sony list since its actually a remake of a PS1 game, kameo added to MS list.