To be released in 2008, Toy story 3 was originally planned to be
produced without Pixar's involvement, as part of Disney's
production deal with the company at that time, Disney had the
rights to produce some sequels to Pixar features without their
involvement.
This scenario upset many. In Jan 2006, Disney announced a deal to
acquire Pixar. Almost immediately after the announcement, Pixar
co-founder and Disney's newly appointed Chief Creative Officer John
Lasseter halted production of the film. Reason being "Sequels
should only be made if there is a really great story that demands
it, and should be the domain of those who created the original
film".
In Feb 2006, however, Pixar took over production from Disney. In
May 2006, Disney announced that the film was in full production.
The script is currently being rewritten.