Second try: this should work multiplatform.

Author: aleyush

binding.gyp

@@ -3,28 +3,34 @@
     {
       'target_name': 'binding',
       'conditions' : [
-        ['OS=="win" and "<!@(cmd /C where /Q pg_config || echo n)"!="n"',
-          {
-            'sources': ['src/binding.cc'],
-            'include_dirs': ['<!@(pg_config --includedir)'],
-            'libraries' : ['libpq.lib'],
-            'msvs_settings': {
-              'VCLinkerTool' : {
-                'AdditionalLibraryDirectories' : [
-                  '<!@(pg_config --libdir)\\'
-                ]
-              },
-            }
-          }
-        ],
-        
-        ['OS!="win"',
-          {
-            'sources': ['src/binding.cc'],
-            'include_dirs': ['<!@(pg_config --includedir)'],
-            'libraries' : ['-lpq -L<!@(pg_config --libdir)']
-          }
-        ]
+        ['OS=="win"', {
+          'conditions' : [
+            ['"<!@(cmd /C where /Q pg_config || echo n)"!="n"',
+              {
+                'sources': ['src/binding.cc'],
+                'include_dirs': ['<!@(pg_config --includedir)'],
+                'libraries' : ['libpq.lib'],
+                'msvs_settings': {
+                  'VCLinkerTool' : {
+                    'AdditionalLibraryDirectories' : [
+                      '<!@(pg_config --libdir)\\'
+                    ]
+                  },
+                }
+              }
+            ]
+          ]
+        }, { # OS!="win"
+          'conditions' : [
+            ['"y"!="n"', # ToDo: add pg_config existance condition that works on linux
+              {
+                'sources': ['src/binding.cc'],
+                'include_dirs': ['<!@(pg_config --includedir)'],
+                'libraries' : ['-lpq -L<!@(pg_config --libdir)']
+              }
+            ]
+          ]
+        }]
       ]
     }
   ]