Update protobuf version
diff --git a/.gitmodules b/.gitmodules
index 4ca1b8d..008bc5f 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -4,7 +4,7 @@
 [submodule "third_party/protobuf"]
 	path = third_party/protobuf
 	url = https://github.com/google/protobuf.git
-	branch = v3.0.0-alpha-4.1
+	branch = v3.0.0-beta-2
 [submodule "third_party/gflags"]
 	path = third_party/gflags
 	url = https://github.com/gflags/gflags.git
diff --git a/examples/cpp/helloworld/Makefile b/examples/cpp/helloworld/Makefile
index f2093af..d7c4b77 100644
--- a/examples/cpp/helloworld/Makefile
+++ b/examples/cpp/helloworld/Makefile
@@ -92,7 +92,7 @@
 	@echo "Please install Google protocol buffers 3.0.0 and its compiler."
 	@echo "You can find it here:"
 	@echo
-	@echo "   https://github.com/google/protobuf/releases/tag/v3.0.0-alpha-1"
+	@echo "   https://github.com/google/protobuf/releases/tag/v3.0.0-beta-2"
 	@echo
 	@echo "Here is what I get when trying to evaluate your version of protoc:"
 	@echo
diff --git a/examples/cpp/route_guide/Makefile b/examples/cpp/route_guide/Makefile
index b906177..dd72e3d 100644
--- a/examples/cpp/route_guide/Makefile
+++ b/examples/cpp/route_guide/Makefile
@@ -86,7 +86,7 @@
 	@echo "Please install Google protocol buffers 3.0.0 and its compiler."
 	@echo "You can find it here:"
 	@echo
-	@echo "   https://github.com/google/protobuf/releases/tag/v3.0.0-alpha-1"
+	@echo "   https://github.com/google/protobuf/releases/tag/v3.0.0-beta-2"
 	@echo
 	@echo "Here is what I get when trying to evaluate your version of protoc:"
 	@echo