Quijaua

<?php
$tags = wp_get_post_tags($post->ID);
if ($tags) {

$first_tag = $tags[0]->term_id;
$args=array(
'tag__in' => array($first_tag),
'post__not_in' => array($post->ID),
'posts_per_page'=>4,
'caller_get_posts'=>1,

Quijaua

<select name="estado">
<option selected="" value="">Selecione o Estado (UF)</option>
<option value="Acre">Acre</option>
<option value="Alagoas">Alagoas</option>
<option value="Amapá">Amapá</option>
<option value="Amazonas">Amazonas</option>
<option value="Bahia">Bahia</option>
<option value="Ceará">Ceará</option>
<option value="Distrito Federal">Distrito Federal</option>
<option value="Espírito Santo">Espírito Santo</option>

Quijaua

<select>
    <option value="">Selecione</option>
    <option value="AC">Acre</option>
    <option value="AL">Alagoas</option>
    <option value="AP">Amapá</option>
    <option value="AM">Amazonas</option>
    <option value="BA">Bahia</option>
    <option value="CE">Ceará</option>
    <option value="DF">Distrito Federal</option>
    <option value="ES">Espirito Santo</option>

Quijaua

AC
AL
AP
AM
BA
CE
DF
ES
GO
MA