I\'m trying to post a moment in google+ using the API, creating a simple example, but I get a 401 error. I\'m following Silvano Luciani steps from https://plus.google.com/+S
You need to use the version of the library that you can find in trunk for the code shown in the gist to work.
You shouldn't use Google_PlusMomentsService, because it has been deprecated (and it's removed from trunk). It's strange that Google_PlusService doesn't exist, it's here.