Hi Ernst - I read your blog post.
It seems to me that your assumption that the author is the viewer when the node is viewed one time is plausible, but not ironclad. It probably works if the data is not really important, but in a real-life situation a race condition on viewing could have someone else view it before the node creator.
-Randy
Thanks Piere! It does exactly what I wanted to do.
See this blog post for more information http://www.pluess-production.ch/content/show-drupal-node-exactly-one-time
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Ernst