I noticed that the net.socket.asd file calls CFFI-GROVEL:GROVEL-FILE, which is undefined by the cffi-grovel system provided by the cffi-net darcs repo. Is cffi-net the correct source of iolib's cffi-grovel dependency?
you need to pull this cffi and its dependencies (it's about to be merged back into the official cffi branch):
darcs pull http://common-lisp.net/~loliveira/darcs/cffi+lotsastuff/