Do Android 3.0 tablets have standby/hibernate mode? I am considering an Acer Iconia A500 device as a book reader. Having years of experience with using (and programming) different devices (PDAs, smartphones, tablet PC, book readers), I am used to charge the reading device (whichever I use) only once in a week or so. When I don't read, I hope to have it in sleeping mode consuming only minimal energy (as it's a bookreader, I don't need it running any background apps or hanging on the net). 

So the question is - do Honeycomb devices have a true standby mode which can keep the battery for a week or so (and let the device power on in less than 10 seconds), and not just "sleep" mode we see in Android 2.2 smartphones? 

Update: got myself the above mentioned device. It holds power for about a week when not used, so I guess this is close to what I would like to have with sleep mode.
As far as I'm aware, Android basically just doesn't work this way. You can turn off the screen ("sleep" mode) and put it into airplane mode for some extra battery saving, but there's no "standby" equivalent like on a laptop. The processor should underclock itself when you do this, too (how much probably depends on the device). And, as Lie Ryan points out in the comments, for phones this is largely due to the fact that a call could come at any time. I'd guess Honeycomb's behavior is essentially a hold-over from that since it's easier than rewriting it.

That being said, if you just want a book reader, you might consider something like a Nook Color. The Iconia is really a full-fledged tablet PC (though running Android), but something designed specifically for e-reading will probably offer better battery life.