Here's a BPL thread on Bill Fornshell's cuben hammock:
Hammock weight has so many variables: rigging, bug protection, insulation, tarp, and the hammock itself. You could get pretty light with a Speer-type hammock (top-entry), cc foam pad and poncho-tarp, but this depends on your need for bug netting and warmth. Take a look at hammockforums.net and Just Jeff's site at www.tothewoods.net. Lots of nice folks over there (some, but not all, are even concerned about weight!).