From a press release issued by Dorna:

Some changes of dates were made to the 2005 Grand Prix calendar. The Italian and Catalunya Grand Prix will both be scheduled a week later, respectively on June 5 and June 12. The British Grand Prix will be held on July 24, and the German Grand Prix a week later, on July 31. The Malaysian Grand Prix in Sepang will be held on September 25, between the Japanese Grand Prix and the Qatar Grand Prix.

Grand Prix Circuit

4/10 Jerez, Spain
4/17 Jacarepagua, Rio ***
5/1 Shanghai, China
5/15 Le Mans, France
6/5 Mugello, Italy
6/12 Catalunya, Spain
6/25 Assen, Netherlands **
7/10 Laguna Seca, United States *
7/24 Donington Park, Great Britain
7/31 Sachsenring, Germany
8/28 Brno, Czech Republic
9/18 Motegi, Japan
9/25 Sepang, Malaysia
10/1 Doha, Qatar **
10/16 Phillip Island, Australia
10/30 Estoril, Portugal
11/6 Valencia, Spain

*: Only MotoGP class
**: Saturday
***: Subject to contract