AFAIK, Excite AU has its own CGI to handle submissions (with a special hidden input field that identifies the submission as coming from excite.com.au), but they don't seem to have any spider IPs associated with them.
So my guess is that Excite AU's passing the submission to excite's database, very much like what Altavista does.
Now if they update just as often then it'll be fantastic :p
Seems to me they are independent. I have a few useless pages in the Australian Index which aren't anywhere in the US site. Prior to June I was getting good referrals and had my home page fairly well ranked. Then my homepage disappeared from the index :( All that's left are some useless pages(the support stuff like About Us, Contact, Press Releases etc) Can you believe it - they (Excite Support) keep telling me I need to add some 'pertinent' content to my homepage such as what's on my About Us page which couldn't be any less pertinent I assure you. I submitted a professionally optimised doorway page 6.5 weeks ago so I'm waiting to see if that appears within the 8 week time frame. If anyone can give me a credible reason why Excite Aus doesn't like my homepage I'd sure like to hear from you.
Sorry to drift off topic, but my bet's on separate databases, but no doubt Woz will get the answer. (BTW I am optimistic of reappearing in Altavista Australia quite soon thanks Woz)