<div class="clearfix">
    <div id="left">
        Nome [text* your-name] <br/>
        E-mail [text your-subject]
    </div>
    <div id="right">
        Assunto [email* your-email] <br/>
        Telefone [tel tel-207]
    </div>
</div>

Mensagem [textarea your-message] <br/>

[submit "Enviar"]

Css

/*--- form 2 colunas ---*/
#left {
width: 49%;
float: left;
margin-right:2%;
}

#right {
width: 49%;
float: left;
}

.clearfix:after {
content:"\0020";
display:block;
height:0;
clear:both;
visibility:hidden;
overflow:hidden;
margin-bottom:30px;
}

.clearfix {
display:block;
}
/*--- form 2 colunas fim ---*/