I worked with a large website that had many translations and three English websites (.com, .co.uk, and .com.au). The only differences between the three English websites were a few spelling and wording changes (flashlight -> torch, localize -> localise, etc), the currency shown, and the products that were featured on the homepage customized to local tastes.
With the top level domain, Google eventually seemed to get the targeting right (although it looked like they made an algorithm change in January 2009 to make that happen). All three were hosted in the US, we probably could have done better with local hosting.
My current website is translated, but not localized (I just have one English website.) It seems to rank well enough in UK, Australia, and India that I'm not planning to localize it at this time. I'm not sure what I've done to make that happen though.