prova così:

codice:
<form id="form1" name="form1" method="post" action="">
		<label>Menu a tendina con group
		<select name="select">
				<option selected="selected">Scegli</option>
				<optgroup label="Regioni">
					<option value="lazio">lazio</option>
					<option value="campania">campania</option>
				</optgroup>
				<optgroup label="Comuni">
					<option value="anzio">anzio</option>
					<option value="cerveteri">cerveteri</option>
				</optgroup>
		</select>
		</label>
</form>
ciaux