>So I decided to try out Ubuntu on a different partition.  I built Ruby
>1.8.3, and now in irb I can't hit the up arrow to bring up my last
>command(s).  Is there a way to set this up?  I'm asking because I'm a
>terrible typist and require this much-needed tool (crutch).

Before building ruby, check you have installed the following packages:
libreadline[4 or 5]-dev
libncurses[5 or w5]-dev

Regard,
Yuri Kozlov