Smartphones or flash drives to replace the laptop (?)

I am intrigued by the possibility to leave my laptop at home (or work) instead of carrying it around every single day, as discussed in this WSJ article. Are we already there?

I have been running a small experiment on myself for the past few months about the feasibility of this approach. My use case is one with heavy usage of my Outlook mailbox, lots of documents, and some software like MS Office, Emacs and Matlab.

In my experiment I have stored all my working data files in an 8 GB Sandisk cruzer USB drive. I plug the cruzer drive into various computers I have access to, just as I would a smartphone with so much flash memory. It mostly works (i.e. I don't miss my laptop), but here are the unresolved issues

1. Security: Yes I mean the consequence of loosing the flash drive (smartphone), but also the issue with secure corporate Outlook email on my laptop via VPN and certificates. It is impossible to have the same corporate setup at home on another computer (at least where I work). But this may not be an issue for those who use web mail.

2. Software: Well lets face it, not all software can be installed on every computer. The other option is trying to install software on the flash disk, but then many software installations bind themselves to the computer - for example - those registry keys of MS Office installations. Perhaps this is an area where more innovation is needed to untether software from hardware. For now, I use my computer agnostic Emacs editor as my data input tool out side of my laptop. Oh, and I also use it when I am on my laptop. I love it!

3. Customization: There are ways to copy your browser favorites, screen savers, wall papers etc. on your flash drive or smartphone, but I would say figuring all this out is cumbersome. Instead there is this cool Mokafive concept of carrying your whole OS and data and customized software all on one flash drive! Just boot off the USB drive and you are done. I found out from the IT guys though that security software will complain about this. Another problem is that loading and running an OS off the USB drive will be slowwwwwwwww.