Falkor wrote
You'll need to follow the action plugin howto, and "catch" the event IO_WIKIPAGE_WRITE. Then you can
append the text you need to your entry. The data to be saved is in the array $data[0][1].
I doubt that IO_WIKIPAGE_WRITE is the right event to hook in because as I understand it, jossif wants the replace the @USER part dynamically depending on the current logged in user and not only when the wiki page is saved (keep caching in mind).
I think a syntax plugin would be enough. Have a look at the var plugin [1]. I think it would be easy to modify it to fit your needs.
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chi
[1]
http://wiki.splitbrain.org/plugin:var