There's a way to get it working.
First, get an invite. Hit me up with your gmail and I'll send one your way.
Unfortunately, upon clicking the invite, it will say "Sorry, Google Music Beta is only available in the United States".
Here's what you do. Download
TunnelBear - it's free - and you'll get a little program that looks like this:
Flip the left switch to "On" and the right switch to "US", wait about 20-30 seconds until it says "Connected" and BOOM! Your computer now thinks it's in the US. Now click the invite in your mail and sign up for Google Music and it'll work. You can then turn off TunnelBear - as the Google Music country lock is only on the activation page, once you get past that, you're golden.
Then, simply do a google search for "Google Music Beta apk" and you'll find any number of links to manually install the APK to your device. Once installed, it'll ask you to sync, do that, and you're sorted.
Bonus - TunnelBear also works for any site that requires you to be in the US to use, like MTV, Hulu, etc etc. I use it all the time when video clips pop up with that stupid country lock message. Win.