Upgrading ruby
$ sudo apt-get update
$ sudo apt-get install ruby-odbc-dbg
$ sudo apt-get install ruby1.9
$ sudo ln -sf /usr/bin/ruby1.9.3 /usr/bin/ruby
# Log out of the vm via exit, then log back in via vagrant ssh
$ ruby -v
ruby 1.9.3p0 (2011-10-30 revision 33570) [i686-linux]