Global Service Monitor for System Center 2012 SP1 Operations Manager is now available. However, it’s not quite as simple as your normal feature in OpsMgr, because there is a cloud service involved.
Version 1.0.1800.0 of the System Center Global Service Monitor Management Packs can be downloaded and installed freely. Then you are going to need an account for Global Service Monitor. On this, Microsoft says:
You can sign up for a free trial account and use Global Service Monitor for free for up to 90 days. Beyond the 90-day free trial period, System Center Global Service Monitor is only available to customers with active Microsoft Software Assurance coverage for their System Center 2012 server management licenses.
This Software Assurance benefit will be available in March 2013 in supporting countries. At the moment, these are Australia, Austria, Brazil, Canada, France, Germany, Ireland, Italy, Japan, Mexico, Netherlands, Singapore, Spain, Switzerland, United Kingdom, and the United States.
So, if you want to use GSM long term, you will need to be (a) in one of the participating countries, and (b) have current Software Assurance on your System Center licensing. Beyond that, there is no additional cost that I can see.