This is untested, but you could add another parameter to your shortcode to contain the URL of the link:
[team][team_member name='Michael Peacock' img='http://tdp-arch.com/wp-content/uploads/2012/11/michael1.jpg' position='Intern Architect']url='http://mysite.com/profiles/mpeacock' [/team_member][/team]
and modify the code to use that URL:
function team_member( $atts, $content = null ) {
extract( shortcode_atts( array(
'name' => '',
'position' => '',
'img' => '',
'url' => '',
), $atts ) );
$return = '
<li>';
if ($url) $return .= '<a href="'.$url.'" >';
$return .= '<img class="imgWithBorder" src="'.$img.'" alt="" />';
if ($url) $return .= '</a>';
$return .= '<p>'.$name.' <span>'.$position.'</span></p>';
$return .= '</li>
';
return $return;
}