No, that's wrong, it is not valid syntax, ampersands in query strings as part of in-page markup need to be escaped:
http://validator.w3.org/docs/help.html#faq-ampersand
http://htmlhelp.com/tools/validator/problems.html#amp
The browser will correctly unescape it, so it should work fine.
It's a very common error, but it will cause W3C validation to fail.