Having used the Sony PRS-505 now for a few weeks (mainly to read dissertations and project reports) I have quickly gotten used to carrying less weight. The user interface requires some learning - as the screen is pretty slow pressing a button does not give immediate feedback and that feels strange - more than expected. I wonder if there are studies on traditional interacton with electronic paper? Another issue: it seems to depend on the crew whether or not it is OK to read from an eBook during the entire flight (including take-off and landing)...
While reading a thesis I was reminded of an interesting paper on tangible programming  from a special issue of Personal and Ubiquitous Computing we did in 2004. The paper situates the topic historically and gives an interesting introduction.
In recent meetings as well as in airports around the world one can observe a trend: wired telephony! Whereas people with traditional mobile phone walk up and down and talk on the phone iPhone users often sit wired up to the next power plug an phone... seems apple has re-invented wired telephony ;-) and other brands will soon follow (make sure to reserve a seat with a power connection).
 McNerney, T. S. 2004. From turtles to Tangible Programming Bricks: explorations in physical language design. Personal Ubiquitous Comput. 8, 5 (Sep. 2004), 326-337. DOI= http://dx.doi.org/10.1007/s00779-004-0295-6