Personally I have always been bothered by this too, but not to login. If you watch one of the many Intel Mac vs PPC mac bootup videos, regardless of how long it takes the OS to start up, the Intel mac always has an unfair advantage IMO. The Intel macs firmware initializes way faster than PPC macs do. Not only do they chime (bong) quicker, but from the chime to the OS even starts booting up is faster. If you take a G5 quad vs a Core Solo Mini, the mini will boot up faster just because the Open Firmware on the powermac takes so long in comparison. For it to be fair, you'd have to turn the PowerMac on, wait couple seconds and then turn on the Mini.
I'm a firm believer that not all Intel macs actually get to the desktop or login screen faster than PPC ones do; it just seems like it because the OF takes so damn long vs the EFI.