Mount Google Drive in Linux?
Grive or inSync is a file sync tool which syncs up a local file system and remote Google Drive. You cannot "mount" Google Drive using these tools.
For mounting, use google-drive-ocamlfuse, FUSE-based filesystem for Google Drive.
Installation instructions, and more details about configuration, and authorization are at the Installation of FUSE filesystem over Google Drive wiki page (on GitHub).
The project's GitHub homepage also has the readme file that is for the google-drive-ocamlfuse
source code.
Here are distro-specific instructions to mount Google Drive with google-drive-ocamlfuse.
An open source client for Google Drive exists: Grive.
For now, the application is considered experimental and it lacks full sync, but it can upload and download new or changed files already (so you can access your files offline). What it can't do yet is: wait for changes and automatically sync the files or delete files (when a file is deleted locally, it's ignored and when it's deleted remotely, it's reuploaded if it exists locally).
Sources and binaries are available on Github. A third party, webupd8, has provided a PPA for Ubuntu.
Note that this project is officially abandoned since September 2018.
There is an SDK available, so someone will probably make a linux solution soon. There is also a drive on Google+ going on right now to get Google to add a Linux client, in addition to the Windows, Mac, and Android clients (not to mention their plans for an iOS client.)
Then they will be on par with Dropbox :) (with a bit more extra free space by default)