I have installed TikZ/PGF using Synaptic Package Manager. Still it contains version 2.0. Now How do I update it?
Sourceforge has a
.tds.zip file, which means it is a snap to install in a vanilla Ubuntu TeX Live (2009) environment. Download the file; move it to the base of your TeX tree (for me that is
/usr/share/texmf-texlive/); unzip the
.tds.zip file; run
sudo texhash; and you're done.
Of course, to manipulate files outside of your 'home' directory, you probably need to use
Edit: In fact, as @Caramdir pointed out, Ubuntu 11.10 (and presumably 12.04) have PGF 2.10 installed independently of whatever version shipped with TeX Live 2009, which is the latest version except for those who like to live on the bleeding edge (if a
CVS version can still be called the bleeding edge!).