I think that considering 'old' a locatedb older than 1 hour is a little overkill, keep in mind that periodic maintenance tasks update it only weekly.
Another mean to be sure locate db (and other maintenance tasks) are regularly run is using the free PseudoAnacron (available on http://www.jaw.it/pages/en/x_misc.html page).

just a couple of comments.

1. Rebuilding the database is no longer part of the weekly maintenance script. The launchd trigger, stored in /System/Library/LaunchDaemons/ as com.apple.locate.plist and was supposed to launch at 3:15 AM on Saturdays, has been disabled. So, if you want to rebuild the database, you have to do it manually.

2. The locate.updatedb executable is crippled, excluding some system-level items. To rebuild it so nothing's missing, you need to replace the current locate.updatedb executable with the uncrippled one from Leopard, located in its /usr/libexec/ folder, assuming that you still have an early Leopard installation or installer. I believe it was crippled in 10.5.5 (one dated 12/12/08 or earlier will work uncrippled).

Supposedly, Apple crippled it as a security measure, but since I'm on a single-user machine, there's no sound reason to preclude searching everywhere. That makes it better than Spotlight for searching for named items anywhere.