Enqueue script on every page except one

Try giving your function its own parameters and do a template_redirect, something like this:

<?php
  function mypage_scripts() {
    if ( !is_admin() ) {
      wp_deregister_script('jquery');
      wp_register_script('jquery', 'http://ajax.googleapis.com/ajax/libs/jquery/1.6.2/jquery.min.js', true, '1.6.2', false);
      wp_enqueue_script('jquery');
      /* My Script */ 
  function contact_form_script() {
      if ( !is_page('contact') ) {
        wp_enqueue_script('myscript', get_bloginfo('template_url') . '/js/myscript.js', array('jquery'), '1.1', false);
        }
      }
  add_action( 'template_redirect', 'contact_form_script' );
    }
  add_action( 'wp_print_scripts', 'mypage_scripts');
  }
  ?>

I’ve not checked this, but I believe it will work.

I Checked this one on on one of my themes and it worked:.

<?php
  function mypage_scripts() {
    if ( !is_admin() ){ 
    wp_deregister_script('jquery');
    wp_register_script('jquery', 'http://ajax.googleapis.com/ajax/libs/jquery/1.6.2/jquery.min.js', true, '1.6.2', false);
    wp_enqueue_script('jquery');
      }
    add_action( 'wp_print_scripts', 'mypage_scripts');
    }
  function contact_form_script() {
      if ( !is_page('contact') ) {
        wp_enqueue_script('myscript', get_bloginfo('template_url') . '/js/myscript.js', array('jquery'), '1.1', false);
        }
      }
  add_action( 'template_redirect', 'contact_form_script' );
  ?>

NOTE:
The one thing I did diferent on my test is I wasn’t using the Google scripts. Maybe that is giving you the issue?