Hi,
Apparently, an eReader with eInk displaying a page will not consume much energy (if any?) unless you turn to another page.
If this is correct, why switching off the device at all?
It´s a doubt a got, any ideas welcomed.

The e-ink display doesn't consume any energy until you turn the page but the rest of the components do. The CPU and memory are still consuming power and there has to be circuitry checking for page turns. Most devices can go into sleep mode which puts the rest of the components into a low power state without shutting the device completely off. It's confusing if you're not used to it because when the battery fails completely there is still text on the display.
That is correct, and also the power usage in sleep mode can be fairly minimal, which is why the battery lasts so long. In the case of the Kindle, the on/off button doesn't actually switch the Kindle off, but puts it into sleep mode (although the manual just keeps it simple by telling you it is off ). The only time it is actually off is when you reboot it.

You can think of it as a standard sleep and a deep sleep (standard sleep still displays the screensaver, press the power button for a little longer to put it into deep sleep and the screen is blank). It's not fully switched off as when you press the power button to turn it back on, it loads instantly and you don't have to wait for it to boot up.
Thank you both for your attention.

It does make perfectly sense the way something needs to be running in the background in order to check what the status of the device is at any given moment.

Now I will have to inform myself better regarding how the mysterious e-Ink works =) [love that "when the battery fails completely there is still text on the display" sentence"]
http://en.wikipedia.org/wiki/Electronic_paper

Oops...didn't notice how old the thread was!
Do you really think that a person who hasn't logged into MR since last August still actually cares?