Yeah, Google are a bunch of dicks and left Linux users out in the cold with Google Music. At least for now. No native client for Linux and not even a damn web-based upload option like Amazon Cloud has. Thankfully there's a way to get it working.
Ok, don't give a shit if you already have Wine installed. So did I, then Google Music Manager started freezing. So install the Wine repository and update/install Wine:
sudo add-apt-repository ppa:ubuntu-wine/ppa
sudo apt-get update
sudo apt-get install wine
Then go grab the super easy install script here.
Then navigate to the directory where you unzipped the script package and run this to install it:
chmod +x install.sh
That's it, you're done. The script should automatically put a shortcut icon in your Internet programs folder.