It looks like the 2008 edition of the Vodafone Delhi Half Marathon has been rescheduled to Nov 9th, as per the update at AIMS Marathon calendar. I guess this is for the benefit of all runners, since the weather would be much better compared to most of the previous runs which were generally held around mid-October.
Still a good 5 months to go, but it never hurts to start early, especially if you want to do something good.