If you want to run on the bleeding edge, or help develop Meteor, you can run Meteor directly from a git checkout.
git clone git://github.com/meteor/meteor.git
If you're the sort of person who likes to build everything from scratch, you can build all the Meteor dependencies (node.js, npm, mongodb, etc) with the provided script. This requires git, a C and C++ compiler, autotools, and scons. If you do not run this script, Meteor will automatically download pre-compiled binaries when you first run it.
Now you can run meteor directly from the checkout (if you did not build the dependency bundle above, this will take a few moments to download a pre-build version).
From your checkout, you can read the docs locally. The /docs directory is a meteor application, so simply change into the /docs directory and launch the app:
You'll then be able to read the docs locally in your browser at http://localhost:3000/.
Note that if you run Meteor from a git checkout, you cannot pin apps to specific Meteor releases or run using different Meteor releases using --release.
Aside from a short launcher shell script, Meteor installs itself inside your home directory. To uninstall Meteor, run:
rm -rf ~/.meteor/
sudo rm /usr/local/bin/meteor
On Windows, just run the uninstaller from your Control Panel.