Create a sensible package cache directory on Windows.

utils/pub/pub.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 /**
  * The main entrypoint for the pub command line application.
  */
 #library('pub');
 
 #import('../../pkg/args/lib/args.dart');
@@ skipping 62 matching lines @@
     printUsage();
     return;
   }
 
   // TODO(nweiz): Have a fallback for this this out automatically once 1145 is
   // fixed.
   var sdkDir = Platform.environment['DART_SDK'];
   var cacheDir;
   if (Platform.environment.containsKey('PUB_CACHE')) {
     cacheDir = Platform.environment['PUB_CACHE'];
+  } else if (Platform.operatingSystem == 'windows') {
+    var appData = Platform.environment['APPDATA'];
+    cacheDir = join(appData, 'Pub', 'Package Cache');
   } else {
-    // TODO(nweiz): Choose a better default for Windows.
     cacheDir = '${Platform.environment['HOME']}/.pub-cache';
   }
 
   var cache = new SystemCache(cacheDir);
   cache.register(new SdkSource(sdkDir));
   cache.register(new GitSource());
   cache.register(new HostedSource());
   cache.sources.setDefault('hosted');
 
   // Select the command.
@@ skipping 157 matching lines @@
     print('');
     print('Usage: $usage');
 
     var commandUsage = commandParser.getUsage();
     if (!commandUsage.isEmpty()) {
       print('');
       print(commandUsage);
     }
   }
 }