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None so far. It seems that XOOPS users have to resort to seperate software to host an auction. My problem with this is that (on all that I've seen) it takes you to a completely different area of the site. This is no good for me since I would like to tie the auction in with the gallery, rating and forums.
However, I do see that PHPnuke has auction modules - but I have no idea if this is any good since I have never used it.