Crash.net have published a leaked calendar (nicked from The Grauniad):
http://www.crash.net/f1/news/148803/...ar_leaked.html
Pure speculation on the part of The Guardian, so I take it with a bucketful of salt.
I suspect the link will be removed quickly so I have listed the circuits below:
3 March Buenos Aires Argentina Last hosted F1 in 1998
21 March Mexico City Mexico Last hosted F1 in 1992
11 April Jerez Spain Last hosted F1 in 1997
25 April Portimao Portugal Never hosted F1
2 May Imola San Marino Last hosted F1 in 2006
23 May Monte Carlo Monaco Current F1 host
6 June Montreal Canada Last hosted F1 in 2008
13 June Indianapolis United States Last hosted F1 in 2007
1 July Silverstone United Kingdom Current F1 host
25 July Magny-Cours France Last hosted F1 in 2008
15 August Laustizring Germany Never hosted F1
29 August Helsinki Finland Never hosted F1
12 September Monza Italy Current F1 host
26 September Abu Dhabi United Arab Emirates Current F1 host
10 October Marina Bay Singapore Current F1 host
24 October Suzuka Japan Last hosted F1 in 2006
8 November Adelaide or Surfers' Paradise Australia Last hosted F1 in 1995/Never hosted F1