> We're a large organization out of Montreal with several different departments. We could really use an inter-wiki search engine
The only solution I see is using a third party like google. Otherwise you would need to "spider" each of the websites and hold a cache of each page to search against.
Its impossible. unless you have access to the databases, in which can you can mod the code to search over the inter-wiki databases.
Think about it logically. Its not possible unless you use google or something.