The gray Matriarchs were made especially for members of BladeForums, but I don't remember them having any unique markings on the blade that would identify it as being a "forum knife". Someone posted a pic of a prototype on the forum in early '99, I think, and people started clamoring for one. IIRC, forumites helped choose the handle color for the run. I don't know if any other gray handled Matriarchs were made after that.
In the thread pyrguy linked to, Sal mentioned that some of them would also be made available to LEOs. In late '99, I remember seeing the gray handled Matriarch for sale at SFO. There was a little note next to it in the display case which stated that you had to show proof you're in law enforcement in order to buy the knife. It sounds kind of silly now, but that was before the MBC program and Spyderco didn't want to develop a reputation for selling "cheap weapons". The Civilian had been around before that, but it was more expensive and never advertised (I don't think it even appeared in catalogs).