From ZuneRama Forum :

I just bought a new Zune flash player at a local retail store.  I was pretty excited to get it home and loaded with music.  Here's the catch:

IT WON'T WORK UNTIL TUESDAY

If you select any menu it says "To start, visit www.zune.net/setup -- OK"

Under settings it says Version 2.0 (799)
Boatloader 799
Xldr 2.0.799.0

[...]

Ok, there is not much to say about the 8GB flash Zune, except that it seems to be a solid contender quality wise.  The Squircle has a nice feel and response, although the iPod circular motion is maybe a bit nicer.  The combo d-pad/touch sensitive action is responsive and it's tactile feedback is good.

The display is clear.  The font size does cut off the word "Podcast" which was noted in other posts.

The device is inoperable until it gets it's firmware.  The device is not recognized using the current Zune software.  I confirmed this by calling support. 

Support was trying to walk me though setup when I said that I had a new Zune.  They said that the new Zunes weren't out yet and wouldn't be available until Tuesday.  They said I had an old Zune and in trying to prove it, they asked if the back only had a logo on it.  They were surprised when I said it said "8GB".  Then there was a pause followed by a, "can you hold for a minute."  They came back and told me that I was holding "a little bit of the future."  It was also explained that it definitely would not work until Tuesday.

I am enclosing a pic of the screen and the message that you get when you select anything:  music, pictures, video, etc..

If you are trolling the stores for an early purchase, all I can say is that you might be spending your time in vain.  Even if you find one, you will still have to wait until the official release to use it. A sad state to be in, unless you are happy watching it glow!

I hope that this is a satisfying glimpse into the future.