Change line 2419 of /administrator/components/com_comprofiler/comprofiler.class.php from
[code:1]if ( $row ) {[/code:1]
to
[code:1]if ( $row && strlen($row->password) ) {[/code:1]

Should do the trick

@beat: I don't think that you can avoid the double login if you continue to use mainframe->login however given the changes in 1.5 you can avoid it anyway by triggering the user plugins.

The authentication request is only going to every return a fixed set of results in the JAuthResponse, however you could use the JLDAP object to do your own search similar to the code in the LDAP auth plugin to get information about the user back yourself. If you look in the /libraries/joomla/application/application.php file you'll see that you're doing almost all of what the core login function is doing already you just need a few more things to get all the way.

Getting close to having this functionality working it seems

www.joomlapolis.com/component/option,com_joomlaboard/Itemid,/func,view/catid,64/id,78375/#78375