Only thing that's stopping me getting one right now is the need to run Java (runtime should suffice) and a couple of Java apps. Oh and need decent IRC client (must be a usable Chrome app?) and some way to ssh in to server (guess that's possible by default).
I know it's possible to hack a bit, and get Ubuntu install on as well as Chrome, but if I do that, I may as well run stock Ubuntu or other Linux distro.
If I ever get away from that Java dependency, then definitely buying Chromebook.