ErikZ-
Could we not strike a deal with Google similar to the one with Yahoo by which Google favours the original content instead of outdated copies, should be in their interest too.
That seems like the most reasonable course of action. Note, however, that Google is notoriously unresponsive to any queries regarding search result ranking (and who could blame them). Taking this from the bottom up could be difficult. Do we have anyone who has contacts to reasonably high level Google personnel? Has anyone at Google ever said something about Wikipedia?
There are other options aside from downranking Wikipedia mirrors. Google does have a deal with reference.com, whereby when you enter a word like "elephant", it provides a link to a dictionary [definition]. I'm not sure if reference.com pays them for that, and if so, how much. I could imagine a similar link [encyclopedia article] for searches which match Wikipedia titles.
We do need to enforce the FDL requirements more systematically. phatnav.com, for example, leeches our images, but does *not* provide a backlink to Wikipedia articles and even calls itself "a Wikipedia". This is a violation of the FDL and of our trademark.
While these mirrors do hurt our rank, they have the effect of getting multiple Wikipedia articles into many search queries. I hope this will not be perceived as search engine spamming.
Regards,
Erik