Mark found a bug in the backend but it’s been discovered already and discussed. I applied my own fix below..
Warning: join(): Bad arguments. in …/wp-admin/edit.php on line 13
if( is_array( $editable ) == false )
$editable = array( "1" );
$editable = join(',', $editable);
On another note, if you can’t post blog entries as anything other than “Draft” or “Private”, then go to Options->Writing and check “May publish articles” for “Newly registered members:”
Now, if only we could set publishing rights to a certain user level, then new users could publish if the admin set their level high enough.