Unity3 shader: something's changed?

I'm trying to get the Fur shader (from script wiki) working in 3.0. Worked fine in 2.6, partially in 3.0 beta 6, and not at all in beta 7.

I get this error 'expression left of ".fog" is not a struct or array at line ...

code looks like

v2f o;
FurVertexPass (0, v, _FurLength, o.pos, o.fog, o.color, o.uv);

v2f btw defined as

struct v2f {
  float4 color : COLOR0;
  float4 uv : TEXCOORD0;

Apparently V2F_POS_FOG is a built-in thing? According to http://unity3d.com/support/documentation/Manual/ShaderTut2.html

So, has that built-in thing changed? Any ideas how to proceed? (I'm very new to shader programing as you can tell)

Seems that shader is so old, it doesn't have the fancy new 'surface shader' in it.