Has something happened to libc? (Blam)

[Matthew B Philmon]

When I run Blam I get this:
~$ blam

(Blam:15956): Gdk-WARNING **: locale not supported by Xlib

(Blam:15956): Gdk-WARNING **: cannot set locale modifiers
mono: symbol lookup error: /usr/lib/blam/libblam.so: undefined symbol: 
S_ISSOCK

A googling says the symbol should exist in libc. I've tried building 
Blam from source with the same result.

Matt