<form method="get" id="searchform" action="<?php bloginfo('url'); ?>/">
    <input type="text" value="search..." name="s" id="s" onfocus="if (this.value == 'search...') {this.value = '';}" onblur="if (this.value == '') {this.value = 'search...';}" />
    <input type="submit" id="searchsubmit" value="Search" />
</form>