MSN Music stopped selling music downloads in the US in November 2006, but they have remained available through MSN UK, with the service run by Nokia.  Now, however, that service is set to close in March, according to the MSN Music UK website:

According to a FAQ on the website:

Why is this music download store closing and will there be an alternative?
MSN Music Store will no longer be run by Nokia, as it is today. Instead MSN will launch a new Music Store, and Nokia will continue with Nokia Music Store.

Can I have my account transferred to the new MSN Music Store?
We cannot accommodate this.

And in a German language newsletter item (English translation) announcing the closure, the “exciting new service” is set to launch in May:

from May 2009 you will experience exciting changes on MSN Music. The currently using MSN Music Store closes at the 30.03.2009 and available from may in a new form. Microsoft launches a new, exciting music service. More information about our new service what changed and what we are in the future offer, learn soon.

(Note that this German language version says the service closes on Mar 30, and the MSN UK site says Mar 18, and why is it in German, anyway?)

Will we be seeing Zune powered music downloads available through MSN Music as early as may?  Microsoft has been hinting broadly at coming changes for Zune software, and has recently split the Zune team into hardware and software divisions.  In his call with financial analysts this week, Steve Ballmer talked up Zune software:

We're bringing our services, our gaming service, and our Zune Service, not the Zune hardware but the Zune Entertainment Service, to all three screens, PC, phone, and TV.

Of course its not clear at this point whether the Zune service is coming, as MS seems to love to launch confusing competing services (see: My Phone, Windows Live Sync, Live Mesh), or if the service will launch outside of the UK.  Stay tuned for more.