After having tested Safari for a while, I'm pretty sure I don't like its own way to impose things to the users. To be more clear, if I live in Italy, it's likely I need to use Google.it, so somewhere in the preference panel I would like to find an option to specify my default search engine. The same if I live in UK; and supposing that I hate Google (everything can happen) I should be able to select a different search engine rather than those one Safari propose in its integrated search bar that point to Google.com
Choice, the forgotten word in Apple's laboratories
So whether you are using Safari 3 or Safari 4 it exists Inquisitor, an extension that Yahoo! bought many years ago from an independent programmer and that Today they give it to the web community for free.ty.
Once installed, Safari preference panel show you an additional panel from which - amongst the different things - you can choose which is the default search engine and the language you want to use while making search with Safari.
Inquisitor is also available for Firefox and Internet Explorer (is still in beta), but currently I'm not interested in them anymore.