Hi there,
We have 2 sites, one for Australia, and one for the USA.
We have set the geo targeting to each country, removed all references to Australia on the .com site (except for the image link linking back to our .com.au store), added a US address, changed spelling to US spelling, submitted sitemaps to Webmaster Tools.
Google has only just started indexing the .com US site, however, the .com.au Australia site shows up in a US search when you Google: http://www.google.com/ncr
We also have 2 blogs if that changes or helps anything at all.
Thanks 