While looking at the world in a new way, we can find great sources for primary source, unfiltered information - as you have shown with the Iran Tweets. But I do think there is going to be a period of time where students will need to live in paper AND paperless worlds. Learning how to find authentic and valuable information among the torrent that is raging around them in the paperless world of Tweets, Facebook, and blogs is a skill students don't even know they need. The vast majority of students don't recognize bias and subjective information without some excellent examples to use for comparison. Frankly, right now many of those examples are in print for the vast majority of students because of access.
Access and equity are large, complicated issues. Not everyone has access to Web 2.0 tools, even if they have computer access. Not every student has access to a computer. (One-to-one computer initiatives across the US would help!) Not to dull the cutting edge for you, but some respect has to be paid to those issues in the greater scheme of things. Moving to a paperless teaching environment will take years and some kind of administrative motivation beyond saving the trees.
In terms of living in paper and paperless worlds, I would agree only in the present. Meaning that we are going through a transitional period and were we living in a previous time I think it would be onerous to force the medium of a previous age on the innovation of the next, as in say forcing papyrus on the manuscript editor or goatskin on the village printer.
In terms of access and 1:1 computing initiatives, I have advocated time and time again both here and via my Twitter feed and in various communications and in talks for free universal open access Wi-Fi. This begins in the cities with Wi-Fi initiatives and community access projects. These things are already happening in cities like Philadelphia and Minneapolis. Make it happen where you live.
In terms of hardware, ask your local school district what it costs to educate the average individual student. Then compare to the cost of a Netbook or SmartPhone.
As for motivation: saving trees is great, but this is well beyond even that. This is about our kids actually taking part in the 21st century in an authentic way.
The future is now, whether we are ready for it or not.