Get the ID of the latest post

Been all over looking for the best way to do this.

I want to get the ID of the latest post of a certain post_type.

How can I do this in the cheapest way possible (by cheapest I mean using the least queries, and no loops or post rewinding)?

Surely there is a quick method?

$latest_cpt = get_posts("post_type=yourcpt&numberposts=1");
echo $latest_cpt[0]->ID

The only cheaper way than above, I can think of, would be to write your own SQL query to just return the one post and only the column ID.