After a couple of esoteric post, this is somewhat more practical. At least for those of you in China, who are usering Omniture's SiteCatalyst tool (What, that leaves.... only myself and our team, anyways).
In a recent campaign we discovered that 5 out of the top 10 next pages of our campaign landing page were actually other campaign landing pages of campaigns we were running during the analysis period. There was no direct link on our landing page to any of the other landing pages, so it took some time to puzzle this out.
Out best thesis is the following:

Omniture’s understates a landing page bounce rate significantly if,

1. Your campaigns has a high bounce to begin with AND



2.  You are running several ad campaigns at the same time,
   especially when the campaigns run on the same media AND



3. You are in China. None of our other geos had this problem, which is troubling...

Since Omniture uses a 30 min session timeout, users that
come to a landing page, bounce from there, and click on another campaign banner that lead to the same site within 30 min, are not calculated as bounces. In this situation the 2^nd
landing page will be treated as a “Next Page” in SiteCatalyst's page flow. See graph (click to enlarge):

Taking these “Fake Next pages” into account, we found that our "Non bounced visits" decreased by more that 50%, which basically turns our conclusion on its head. Since we could not directly calculate the bounce rate for the fake next pages (it is not clear how many these fake next pages were coming for entries, as compared to in site traffic) we use a metric that should resemble the bounce rate as closely as possible: Bounce Rate* = (Exits + Fake Next page) / Visits. Its not the WAA definition, but a man has to do, what a man has to do. So here we are, with an even higher higher bounce rate, that almost seems irrational. I will keep you posted on our progress in eating this elephant.