Per default block configuration you can only decide to show a block for certain content types, the other way around requires a little bit of PHP. The following snippet hides a block on nodes of type article and blog:
<?php
// Only show if $match is true
$match = true;
// Which node types to NOT show block
$types = array('article', 'blog');
// Match current node type with array of types
if (arg(0) == 'node' && is_numeric(arg(1))) {
$nid = arg(1);
$node = node_load($nid);
$type = $node->type;
if(in_array($type, $types)) {$match=false;}
}
return $match;
?>