I managed to get this working on Quantal:

1. Add this PPA to your /etc/apt/sources.list:
https://launchpad.net/~gearman-developers/+archive/ppa

2. Install package:
sudo aptitude install gearman-job-server libgearman-dev

3. Install PECL package:
sudo pecl install gearman

4. Add `gearman.so` to you php.ini