Here is an excerpt from Nick's website:
"The time has come.
It is very hard for me to write this, but as all good things come to an end at sometime or another, unfortunately I have to tell you all that my time with Spock’s Beard has come to a close."
Terrible news. I hope it isn't the end for the band. I guess they could get portnoy to replace him.
Here is the full text of the announcement:
http://www.ndvmusic.com/