We decided not to go with multiple TLDs for
SEO reasons. Each TLD is regarded as a separate site by the search engines, so all your linkbacks to your .com site count for nothing when you launch a new TLD. Instead we decided to delineate by country/region via subdirectories - eg
www.yourdomain.com/us and tag the pages using a lang attribute in the html.
An example of this is
www.microsoft.com. Go there and change languages and see what happens.