One time, one guy has come to the office and showed me that Polish characters in a website URL's path part was percentage-encoded. Currently, I'm looking for browser with similar behaviour for testing, but every recent version I have tested have URL's Unicode support. I know only that was Safari, but not if it was Mac or Windows and which version. I have no problems with new Safari on Windows 7.
Which version of which browser on which OS has change characters like
Zażółć gęślą jaźń typed in address bar to something like
You can check it by pasting this
http://www.google.com/Zażółć%20gęślą%20jaźń/ to the address bar and watching how it's changed. The 404 error information is not my interest.