I tried configuring iChat on my mother's managed account (protect the Dock from accidental deletions), but I couldn't use her Gmail credentials (Google Talk option). Jabber and Google Talk were grayed out.
Google tells us ..
... Jabber [and Google Talk] and in Fact Bonjour over iChat are excluded in Leopard when Parental Controls are activated...It doesn't matter that the Parental Controls have no restrictions on iChat or the web. If you enable parental controls, even if all you're doing is protecting the Dock from changes, then iChat can't use Google Talk.
Why not? Why this senseless, irrational, bit of blithering madness that's persisted, without documentation, through 7 point updates to 10.5.7?
Because Apple hates us.
There's a comparable mysterious "Gray out" in iTunes related to iPhone parental controls, but at least that makes a kind of sense.
I hate you too Apple.
Update 4/17/2010: An Apple Discussion post describes enabling Adium functionality even with Parental Controls:
http://*.*.live.comSee also: OS X Parental Controls: The https bug and our family Google Apps services.
By adding the above we were able to Adium to work while still having parental controls turned on.