$(document).ready( domIsReady );

function domIsReady() {

  $("#search").focus( enterSearch ).blur( leaveSearch );

}

function enterSearch(obj) {
  if( $(this).val() == 'Search' ) {
    $(this).val("");
  }
}

function leaveSearch(obj) {
  if( $(this).val() == "" ) {
    $(this).val("Search");
  }
}