Despite being previewed a year ago at the last Google I/O and beaten to the punch somewhat by Amazon (in the States at least), Google Music Locker is on its way.

Expected to be announced later today at Google’s I/O 2011 event in San Francisco, the big deal is that you’ll be able to upload your music to a cloud-based locker and stream tracks to your Android phone and tablet and a Flash-based desktop browser.

All Things D is reporting that you’ll be able to upload a whopping 20,000 songs as well. 20,000 songs that you’ll be able to pull out of the air at will whenever you want.

That’s actual ‘songs’ as well, instead of a 20GB cap you get with Amazon’s Cloud Player. So if you’re worried that your 18-minute prog epics might eat up locker space, you can rest easy. And, it’s all set to be free. Sounds like an incredible deal to us.

But that’s not to say that there aren’t downsides.

First of all, there’s that initial upload. It’s going to be a drag. Especially if, like us, you’ve got a big cache of music that you’ll want to be able to pull out of the air at will on your phone. It reminds us of that scene in Men in Black where Tommy Lee Jones complains about having to buy the White Album again.


Upload, but no re-download

This really wouldn’t be all that bad were it not for the second point. The Wall Street Journal is reporting that though you’ll have to upload your tunes, you won’t be able to re-download them afterwards. This for us is a kicker.

One of the best things about the Android platform and one we keep on mentioning (because it is really useful) is that all of your contacts get saved to your Google Account.

This means that when you sign in to a new Android phone, whatever make, with your Google Account, it’ll start to download all of your contacts, saving you from having to manually input them or back up contacts from the SIM like in the old days.

And now, on phones running 2.3 Gingerbread, this works with apps too.

When we first checked out Gingerbread on our Google Nexus S, we were delighted when we started seeing all of our old apps popping up in the launcher.

We were really looking forwards to being able to sync our playlists in the same way. Plus, after you’ve gone to all the trouble of uploading a big bunch of files, you’d think that you’d be able to get at them later as well.

So why bother to store MP3s in the locker if you can’t get at them? You might as well carry on using Dropbox and ZumoDrive to store/send MP3s, use DoubleTwist to sync your playlists and use Spotify to stream the rest.


It'll be a US-only deal from launch

None of this could matter anyway; like the Amazon Cloud Player, it’s looking like that Google’s music offering will be a US only deal. At least for the time being.

In the same article, All Things D says that an invite-only beta of the service rolls out tomorrow, with a US-wide launch planned “within weeks of launch”.

Jamie Rosenberg, head of digital content and strategy for Android, said “I think we’re honestly going to learn from the beta experience, and think about opportunities for the long-term model,” hinting at future rest-of-world rollout.

We’re sitting tight for Google’s keynote speeches for further information on all of this. The first keynote is due to stream at 5pm UK time this evening.

Update: Not long to go now til the live stream, but we just got tipped to the URL music.google.com/music - although as you can see from the grab above, it's currently only available in the US.