The only thing I've found to be "almost instant" is waking up my mac from sleep mode.

This and the battery performance while sleeping are, in my opinion, some of the main attractions of macs today.

Waking my Windows 7 desktop from sleep is almost instant. It takes longer for my LCD monitors' backlights to flick on than for the login screen to appear.

I've got a Dell Vostro 1510 w/ Vista sitting in front of me, and coming out of sleep is "almost instant."

I know plenty of people are happy with Windows 7 and Vista but with me Windows has such a bad history of crashing/hanging while coming out of sleep/hibernation that I can't trust it.

Oh, I love Ubuntu and am never happy with anything but, but Windows Vista/7 have parity with Macs on resume, and way outpace Linux (if only because the hardware is built for Windows.)

My boss' Vostro was inexplicably hanging on logout/login, that seems to have corrected itself after a few forced reboots. (And I've had that experience a few times on all OS's, including OS X.) Actually, I can't remember it for Linux, but Ubuntu is much less careful about shutting down gracefully than Mac/Windows.

I don't think it's an issue anymore -- every modern machine I have right now (even a netbook running XP) is flawless coming out of sleep/hibernation. From my experience, the vast majority of windows laptop users almost never shutdown their computers.

I've had two machines: an HP DV5000 (AMD/ATI) model and a Macbook Pro. Both of them have not been reliable with sleep mode using a stock Windows XP/Vista install (plus drivers/updates). I haven't tried Windows 7 in sleep mode yet but it's not worth my time to risk losing work. I've only had OSX fail once due to a crash* in sleep mode in 2 years (and over a thousand sleep/wake cycles).

* I've had four failures to wake from sleep due to low battery in a 2 month span I was dealing with an old battery that was failing.

Pressing the home button on an iPad?

Vista (and Windows 7) boot from "hybrid sleep" in less time than it takes my monitor to turn on.

Power draw in "hybrid sleep" is negligible (less than the idle power draw of my 2 LCD monitors in sleep mode).

I thought "hybrid sleep" just meant that the machine is in sleep, but it can also transition to hibernation if your battery runs low.

IIRC it transitions into hibernation after 'x' hours of no activity ( I believe x == 6 ), not sure.