On the http://www.aims-association.org/Calendar.htm website the Great Tibetan marathon date is suppose to be September 9, 2006. But on most other sites including Runner's world it August 17, 2006. The conclusion, Aug 17, 2006 is the correct date for the marathon. Based on my homework done on various sites, the previous race took place in 2005 and in all likelihood it should take place in 2006 as well.
I have tried writing to the organisers to find out more, esp. the registration process but am yet to hear from them. Don't know why they are not responding to my emails.
If all goes well and assuming the race is taking place on Aug 17, I will need to reach Leh by August 10, so that I have a good amount of time to get used to the altitude. I am also trying to find out more details on how one needs to train for a high altitude marathon. This would be a good time to do a half marathon and prepare myself for the Singapore one in December (the gap between the two is just perfect).