For the people who aren't following closely the Sugar project (specially my GNOME friends), if you read in certain media that Negroponte thinks that Sugar is OLPC's biggest mistake, you may want to know that some confusion has arisen from his badly-chosen words.
Negroponte is referring by the name Sugar to the whole OS image that ships in their machines, something different to what everybody else refers by Sugar, even OLPC's own Support FAQ.
No need to extend on this myself because others have explained better the gory details:
Something I can add to those posts though is that OLPC management tried once before to refer to the whole software they made as "Sugar" at one occasion before. It was when the community was outraged at the company's approximation to MS, they announced that their commitment to Sugar was still strong and proof of that was that they had doubled the resources available to Sugar.
What in fact happened was that they hired several people to work on the base system, but the people working on the real Sugar were still the same, sad, 2 and a half people.
Given that the Sugar community is working in the benefit of OLPC's customers, I wonder why Negroponte cannot think a bit more before making such "courageous" statements.