Jeronimo proposed:
Anyway, maybe it is better to have something like this: If a user repeatedly violates some rule, convention, whatever and has ignored pleas from others to follow that rule, we could raise some flag in the database and show the user a page with "Other Wikipedians have not you have repeatedly violated X. Please read this documentation over X. If you disagree with X, please go to Talk:X or Wikipedia-L. If you continue to disrespect X, other measures may follow...".
This I don't like because it puts undue emphasis on rules to consider. Except for NPOV and respect of copyrights, all "rules" here are simply "to consider".
Lee pointed out that the underlying issue is working with others. Perhaps on some prominent page (even the main page?) we could make it explicit that in order to keep this thing going (and we've got a good thing going), playing nice with others is a must. Not so much as a rule or something draconian and non-negotiable, but just a reminder--"hey, look what you're doing. Let's try to work together, and make contributions pleasant and respectful."
Maybe this is too flower-powery an idea to work, but really so is wikipedia itself. :-)
kq