ROR3.beta4 on ubuntu10.04 error

hi, im trying to experiment a rails3 on my ubuntu10.04 32bit, with
installation guide from rails official website

have installed all packages, when i try to run script/rails server

it showed my following errors:

root@c2h2vaio:~/a# script/rails s
/root/a/config/boot.rb:9:in `rescue in <top (required)>': uninitialized
constant Bundler (NameError)
from /root/a/config/boot.rb:5:in `<top (required)>'
from script/rails:5:in `require'
from script/rails:5:in `<main>'

anyone got any ideas? or where should i post this?

btw my ruby version is 1.9.1

ruby -v
ruby 1.9.1p378 (2010-01-10 revision 26273) [i486-linux]

Hi Yiling,

Ruby 1.9.1 is not supported, better upgrade to Ruby 1.9.2-head.

More information here:

http://guides.rails.info/3_0_release_notes.html#rails-3-requires-ruby-187

cheers