USA Style disclaimer: This is my personal opinion and not an official statement of the Arduino team
The official date for launch was always the 26 of March. The distruibutors had been told to wait until this date because a new version of Arduino was needed.
A few days ago we started getting tech support requests from people who bought the board and didn't know what to do with it...
All the distruibutors that started selling before the agreed date, did it because they wanted to make a cheap buck at the expenses of the people who respect agreements.
As far as my vote counts in the Arduino team I will oppose anticipating any new product/idea to those people