I want to run a Javascript console on top of V8. How do I do this?
To build the developer console, rather than the example 'shell' toy application, copy-paste the below commands to your terminal.
sudo apt-get install subversion scons libreadline-dev
svn co http://v8.googlecode.com/svn/trunk v8
cd v8/
scons console=readline d8
These instruction will work for Ubuntu/Debian with a "generic" kernel. For other distributions, you will need to replace the apt-get command with whatever package tool you have available. On 64-bit systems you may need to add arch=x64. The console=readline option enables the readline system, to make it feel a bit more like a standard shell.
More complete documentation here: http://code.google.com/apis/v8/build.html
Note:

See also: Building v8 with GYP