tedster - 5:27 am on Oct 8, 2012 (gmt 0)
Yes, you can create different hostnames (subdomains) for different countries. It might be easier for you to administer, however, I have heard quite a few reports that country-code TLDs have worked out better in practice.
Here's a Google reference that might help - no matter which way you go:
Q: Can I target different English-speaking countries separately with the same content?
A: We recommend using unique and locally-relevant content whenever possible, but we understand that this is not always possible. The "rel-alternate-hreflang [sites.google.com]" annotation can let us know about alternate versions of the same content, which we use to show the optimal URL for the user in search results where your site is shown.
If you do end up using a subdomain schema, I'd suggest verifying each subdomain as a website in WebmasterTools and then geo-targeting each one except perhaps for the "most international" and least localized content. That's probably your plain-old dot-com content.