Getting ViTables
Stable versions
The stable versions of ViTables are available in the downloads area of code Google.com.
In addition, Windows binaries are provided by Python(x,y), a scientific-oriented Python distribution, in this page. Also you can get them (and many other binaries for interesting software) from Christoph Gohlke's website.
GNU/Linux packages
ViTables packages exist for several GNU/Linux distributions, although they aren't always up to date. Some of these distros are: OpenSUSE, Mandriva Cooker, Arch Linux, Debian testing and unstable, Ubuntu, Gentoo and Fink.
Sources repository
Last but not least, you can get the latest (and possibly buggiest ;-) sources from the git repository.