Apple's answer to Intel's new ultrabook asleep-but-still-updating "Smart Connect" thing, Power Nap, which allows your computer to wake up and pull down your email, update software and things, is now available as a firmware update for those already running Mountain Lion.
Unfortunately, you'll need a 2011 MacBook Air or newer, or a gorgeous Retina Display MacBook Pro in the near future, to actually use Power Nap -- that's basically limiting it to new Apple soldered-on SSD-packing machines, which probably means more of Apple's laptops with pre-installed SSDs will see an update at some point.
While on battery power, Apple lists the current Power Nap's activities as pulling down mail; calendar syncs; contact and reminder updating, and other bits and pieces. When you're hooked up to power, though, your Mac will also download software updates and backup to your Time Capsule.
I can see updates and backups while plugged in being a good idea, but I'm not sure I'd be chuffed if my Mac, while cooped up in my sealed bag on my back, clicked on and got boiling hot just to pull down my email, which I could do pretty quickly once I open it up anyway. I guess it's nice to have the option, but me and my trusty non-SSD MacBook Pro will be just fine, thanks. [MacRumors]