After all, there's already a Windows Phone/Windows 8 music app in the Store called "Groove: Smart Music Player." That app, developed by Canadian startup Zikera, is also available for iOS. The Groove player app from Zikera that exists today is powered by Last.FM.
But it seems the new Microsoft Groove and Groove Music Pass have nothing to do with Zikera. When I asked if Microsoft had bought Zikera, a Microsoft spokesperson said "we have nothing more to share at this time."
There's nothing on Zikera's site that indicates they have been bought by Microsoft.
Those currently subscribing to Xbox Music Pass don't need to do anything; they'll automatically get Groove Music Pass. Those who aren't but who are interested: The renamed Microsoft Groove service costs $9.99 a month, or $99 per year.
Microsoft history buffs will recall Microsoft bought a company known as Groove Networks back in 2005 (and got Groove founder Ray Ozzie to join Microsoft as Chief Software Architect in the process). That Groove evolved into what today is SharePoint Workspace and/or OneDrive for Business.