I updated from SlimServer 5.4.1 to 6.0b1.  My player has firmware 40.  My 
server is running on a WindowsXP system.

After the update was complete, I loaded a playlist and played with shuffle by 
song enabled.  The first song plays correctly.  The next song plays correctly 
in terms of the audio, but the now playing display on the SqueezeBox does not 
update.  It still shows the previous song.  That first song remains until I do 
a left arrow to go back to the menu, and then a right arrow to go back to Now 
Playing.  Then it shows the correct song, until it ends and goes to the next 
one.

Interestingly, in some other ways the SB "acts like" the Now Playing has been 
updated.  For example, let's say my playlist is as follows (after the shuffle):

Song A
Song B
Song C
Song D

Let's say when I load the playlist, Song A is first and it plays to 
completion.  Song B will begin playing, but Now Playing will still show Song 
A.  However, if I hit the down arrow to look at the next song in the playlist, 
it will show me Song C.  And if I hit up arrow, I will go to Song B.

Or, instead, let's again say I start on Song A and it plays to completion.  
Song B begins to play, but Now Playing still shows Song A.  If I hit right 
arrow to get song details, it gives me the song details for Song B.  And then 
if I go back with the left arrow, it shows me Song B.

I do NOT observe this problem if I manually skip to the next song using the 
remote control.  If I do that, Now Playing updates correctly to the next song.

As far as I can tell, the web interface always shows the correct song.