I was bored so I made you 2 different solutions.
Solution 1:
Working example: http://jsfiddle.net/Gajotres/b3NR8/
HTML :
<ul data-role="listview" id="custom-listview">
<li class="custom-li">
<div data-role="collapsible" class="custom-collapsible">
<h3>Invite</h3>
<ul data-role="listview" data-inset="false">
<li><a href="#">Email Invite</a></li>
<li><a href="#fb_invite">Facebook Invite</a></li>
<li><a href="#twitter_invite">Twitter Invite</a></li>
<li><a href="#address_book_invite">Address Book Invite</a></li>
</ul>
</div>
</li>
<li class="custom-li-last"><a href="#">Normal item!</a></li>
</ul>
CSS :
.custom-collapsible {
margin: 0 !important;
}
.custom-collapsible h3 a {
border-radius: 0 !important;
border-width:0 !important;
border-bottom-width: 1px !important;
}
.custom-li {
padding: 0 !important;
}
.custom-li-last {
border-top-width: 0 !important;
}
Solution 2 - Inset version
Working example: http://jsfiddle.net/Gajotres/xswkP/
HTML :
<ul data-role="listview" data-count-theme="c" data-inset="true">
<li class="custom-li">
<div data-role="collapsible" class="custom-collapsible">
<h4>Heading</h4>
<ul data-role="listview">
<li><a href="#">List item 1</a></li>
<li><a href="#">List item 2</a></li>
<li><a href="#">List item 3</a></li>
</ul>
</div>
</li>
<li class="custom-bottom-li"><a href="#">Outbox <span class="ui-li-count">0</span></a></li>
<li><a href="#">Drafts <span class="ui-li-count">4</span></a></li>
<li><a href="#">Sent <span class="ui-li-count">328</span></a></li>
<li><a href="#">Trash <span class="ui-li-count">62</span></a></li>
</ul>
CSS :
.custom-li {
padding: 0 !important;
border-width:0 !important;
}
.custom-bottom-li {
border-top-width: 0 !important;
}
.custom-collapsible {
margin: 0 !important;
border-bottom-right-radius: 0 !important;
border-bottom-left-radius: 0 !important;
border-width:0 !important;
}