How do you install or activate PyUno in LibreOffice?

(UPDATING for 2014's)

Perhaps the most used UNO application is document conversion... For this task, in nowadays, you not need UNO, you can use directly

libreoffice --convert-to

About UNO itself, see the new home page, http://api.libreoffice.org/

A good example of using python3-uno (or python-uno) is the Docvert conversor (Docvert for py2).

As said in the response to your comment there: it's an optional installable component for OpenOffice. See the Introduction to Python on OOo page in OpenOffice's Wiki for installation details

I am having the same issue with ubuntu 14.04 and python 2.7.6.

But if you are using ubuntu 12.04, try using sudo apt-get install python-uno.