I recently wanted to update my gem bundle but ran into installation problems with libv8 (requirement for therubyracer):
Installing libv8 (3.3.10.3) with native ext
Ubuntu 11.04
gem "therubyracer", '0.11.1'
gem 'libv8'
Uninstall therubyracer and libv8 gem
Update the bundler gem version
Install lib8-dev package
sudo apt-get install libv8-dev
Then run this
sudo apt-get install build-essential openssl libreadline6 libreadline6-dev curl git-core zlib1g zlib1g-dev libssl-dev libyaml-dev libsqlite3-dev sqlite3 libxml2-dev libxslt-dev autoconf libc6-dev ncurses-dev automake libtool bison subversion imagemagick graphicsmagick libmagickcore-dev libmagickwand-dev
Now install therubyracer manually
gem install therubyracer
It will install therubyracer and libv8 for you.
Now run bundle install
All above steps solved my problem :)