Ok, Jason switched the logging off; it doesn't seem to have made much of a difference. A log of the latest long queries can be downloaded from our sourceforge website:
http://wikipedia.sourceforge.net/long_queries.gz
Regarding the "INSERT DELAYED" idea: I'm not sure that it will help much: the manual states that it's not that useful for the MyISAM tables we are using, since those tables allow asynchronous updates anyway. It's worth a try though.
Another idea is to switch off the query cache (query_cache_size=0): our tables change so frequently that a caching of queries seems to be a big loss.
Axel
wikitech-l@lists.wikimedia.org