[nailer]

Interestingly there's an unreleased Intel version of Mac OS 9 that you see at Apple stories - it's used via Netboot for testing batteries (amongst other things I imagine, but when I saw it it was for testing). Looks like they still (as of late 2010) haven't gotten around to porting some of their old diags to OS X.

[callumjones]

I don't think it is actually OS 9 (how would OS 9 handle the current model SMCs?), I think it just looks like OS 9 but is instead running OS X/Darwin.

[lucaswagner]

It's actually just a tool that runs in EFI; kinda like the AHT. Looks like OS 9, but it isn't.

[nailer]

I wonder why they used the OS 9 L & F? Was very odd seeing it start on a MacBook.

[rplacd]

So that's the secret behind the AHT!