11.10

There is now an unofficial Compiz Plugin that allows you to move the Unity 3D (not Unity 2D) launcher from the left to the bottom.

Credit to WebUpd8.

In summary:

1. You can now peruse the source-code. Contact the maintainer with suggested fixes! Remember this is unofficial and can & probably will have many bugs still to be ironed out.
2. Install the PPA - ppa:paullo612/unityshell-rotated
3. The packages to install are unityshell-rotated libnux-1.0-0
4. A new plugin Ubuntu Unity Plugin Rotated will be made available in CCSM
5. There is a likelihood of freezes on installation. If this occurs use CTRL+ALT+F1 to start a TTY, login and restart lightdm with sudo service lightdm restart. Rerun ccsm to enable the new plugin
6. This plugin replaces the official Unity Plugin. You will obviously not receive further bugfixes from the Ubuntu development team - you will be reliant on the PPA maintainer to supply bug-fixes

warning please see this Q&A as to potential stability issues using CCSM

Linked Questions:

1. What are PPAs and how do I use them?
2. Source code

Sounds like a bug!

The detailed multi-monitor design is being worked out now, for 12.04 LTS. You might want to take a look at the proposed design as soon as a draft is available. Check design.canonical.com for news, or hop into #ubuntu-design to see if a draft is available.