Google Music beta, previously available by invitation only from Google, is opening up its doors a bit starting today with the rollout of invite capabilities.

There aren't many yet - I and everyone else I've seen who have gotten invites, received 2 to hand out, so if you're already a member, log into your Music account, check how many you were granted, and start a bidding war among your friends (fall back to a sword duel in case of disputes).

Note: The beta is available in U.S. only, as evident from the screenshot below.

If you're wondering whether you should care about Google Music (which is available free while in beta) at all, considering we now have Amazon Cloud, Spotify, mSpot, and other services, check out these articles:

• [Deathmatch] Google Music Beta Vs. Amazon Cloud Player
• Mega-Music App Comparison: Google Music v Amazon Cloud Player v Subsonic v PowerAMP v Winamp
• [Review] Amazon Cloud Player For Android - Google Music Who?
• Better Late Than Never: Google Music Manager Now Available For Linux

Source: Google Music (thanks, Omar!)