Thanks for the heads up.
I browsed through a few of their courses here: https://code.google.com/p/course-builder/wiki/ListOfCourses and it seems very much centred on being a MOOC platform rather than an LMS (Is there a difference?) Having looked at the MOOC platforms available at the moment, e.g. Coursera, Udacity and EdX, what they all do is send participants away to othe platforms to do any interaction and/or collaboration beyond their basic discussion forums. Here's a list of the services they offer: https://code.google.com/p/course-builder/wiki/CommunityToolsComparison which you can see is basically doing the same thing but perhaps in a more coherent integrated fashion.
Pros: easier to pull together Google's already existing services into one portal
Cons: doesn't have the kinds of controls and features an experienced LMS user has come to expect from even the most basic LMS'. Everything you add has to conform to "Google's way of doing things" and it may be difficult to add other 3rd party services, for example email services other than GMail, or something as straightforward as a different discussion forum, or a web conferencing service other than Google Hangouts.
There's also Google's blatant disregard for people's privacy rights that has led to some countries, states, and education authorities to implement policies that prevent institutions, organisations, and teachers from using Google services for their work, particularly for keeping admins' ,teachers', and learners' records and data.
There's also thee fact that Google launch these new services, get everyone on them and when they can't find a way to monetise them enough, drop them, leaving anyone who has built up a depency on them scrambling to find alternatives. Think of how many so called open source services Google has axed recently. Now imagine that's your whole LMS and all your records and learning content.
I'd say you're better of with a "real" LMS and then pulling in Google's and others' services as and when you want them with plugins. At least if that service changes or becomes inappropriate, e.g. pulling in inappropriate advertising, or gets axed altogether, or the laws in your region change to protect users' privacy, at least you only have to replace parts of your courses and it'll be easier to find alternatives that'll plug into your existing system.
Just my €0.02!