Update to latest jsonld.js.
--- a/playground/jsonld.js	Thu Feb 14 12:40:58 2013 -0500
+++ b/playground/jsonld.js	Thu Feb 14 12:41:30 2013 -0500
@@ -3709,7 +3709,7 @@
   // options for the value of @type or @language
   var options;
 
-  // determine options for @id based on whether or not it compacts to a term
+  // determine options for @id based on whether or not value compacts to a term
   if(typeOrLanguageValue === '@id' && _isSubjectReference(value)) {
     // try to compact value to a term
     var term = _compactIri(