Just got an email newsletter from the Challenge people announcing a further event for 2010, a HIM in Tyrol, Austria, based at the Walchsee under the Kaiser mountains. Date is 5 Sep 2010 - pretty goodlocation as it's an hour's drive from the Munich, Salzburg and Innsbruck airports. Lake reported to average 20c to 24c temps at that time of year, with drink quality water. Bike course is 90km with 800m climb.
Another one to think about.