I checked after the 10.5.7 update. The Parental Controls log is still broken,if you set the range to anything more than 1 month you get no results:
In theory you can use parental controls to configure managed accounts so that a managed user can change their password.
In practice, when I do that, the managed user cannot click on the Accounts PreferencePane (it's grayed out). So the setting to enable password change does nothing.
Lastly, if you switch a user from managed to standard so you can change their login password and keychain password together, OS X loses all the allowed and disallowed websites configured in Parental Controls. If you switch back to Managed User you start over.
Apple's Parental Controls have been broken in every version of OS X I've used. I think they last worked in Mac Classic version 8 or so.
Why, oh why, can't we customers be more demanding?