Maybe I am just drawing a HUGE blank here, but weren't the capacity increases in February or March? That is not holiday season at all.
The "update" in September last year was more of an adjustment to boost sales based on trends of a new device. The iPhone was a completely new product at that time, and Apple didn't have the greatest idea of what the sales would be like price wise and capacity wise, that is why there were the adjustments last year.
In means of any adjustments or capacity changes any time soon, I just don't see it happening. If Apple were going to do any minor changes, then they probably would have happened during the "Let's Rock" event. The current prices and capacities are plenty popular and probably aren't going to change any time soon.
If anything, Apple would use the Christmas and Holiday season to help get rid of their stock of 8GB iPhones so they could scrap that model come early-2009.