Google Chrome 5 features an integrated Google Translate service
One of the hidden features of Google Chrome 5 is that it comes bundled with an integrated Translation tool.
If your web browser is set to English language and you visit a web page written in some other language, Google Chrome would offer you to translate that page into your default language.
This is a useful service for users who would want to have such a capability in their web browser. However not everyone is pleased.
Google has not provided any option to completely disable this hidden feature. What you can do is disable certain languages or disable it on individual websites.
It remains to be seen if Google provides a front-end to configure this toolbar in future releases.
Update: Newer versions of Google Chrome enables you to disable this functionality.