The relationship between Disney and Pixar has been dead for a while now. Equal parts arrogance, ego, and the decline of a once great company. Its just hitting the press because of the upcoming release of Monsters, Inc.
Toy Story 3 was being used as a bargaining issue about canceling the contract the deal was that Pixar would have produced TS3 and Finding Nemo and been released from the third film. Disney was actually looking at this idea until just about everything at Disney Animation exploded and imploded, and a rather large green gentleman proved to the world that animation without the Disney brand could make a pretty penny or two.
THAT was the key turning point in the whole story. What kept Pixar under Disneys control was the feeling in Hollywood that only Disney had the marketing muscle to put out expensive animated films. Warner Bros, Fox, and others all tried and failed miserably (some with really good films too). After Shrek and Atlantis, Disney couldnt afford to be smug and everyone else saw an opening.
Eisner dropped that deal and is desperately clinging on to Pixar because Disney so desperately needs a hit. Pixar, in the mean time, has been courting a lot of other studios very publicly studios that could throw a large check Michaels way (has anyone seen George recently? Oh thats right, hes getting his trailer ready). There are also rumors that the deal could involve a certain Toy Story animator/director/reason-for-Pixars-success doing another film. This film, by the way, would also be the third in a series and features all kinds of neat creatures (well, everyone except Jar Jar). An interesting little bit to throw into the deal.
Expect a lot of screaming and yelling in the press. But Monsters and Nemo are really looking like the end of the road. And before all the AV, youre an idiot posts show up here, werent there a lot of posts on these boards that Disney DIDNT need Pixar because it had the Secret Lab and Atlantis was going to redefine animation as we knew it? And werent Michael and George soooo tight that the new Star Tours film was just around the corner?