Azure has just enabled a preview feature to monitoring your service availability. This functionality is enabled for Hosted Services, Virtual Machines, Reserved Websites and Mobile Services. Currently you can configure two endpoints to be monitored from up to three global locations. You can configure endpoints from the dashboard or the configuration page
Once you go to Configure Endpoint Monitoring page from the Dashboard enter in your service endpoint URLs and choose some locations (8 worldwide locations are currently supported):
It takes about 15 - 20 mins for availability and performance data to start flowing:
You can also see the last five HTTP responses coming back from the configured endpoints.