When you set up your Windows Azure subscription and get ready to start scripting against it, you will probably find that the Subscription Name is something like "Windows Azure MSDN - Visual Studio Ultimate" or "Azure Free Trial". This isn't too bad, but once you start managing several subscriptions, you will need to differentiate them. It is pretty easy, just go to https://account.windowsazure.com/Subscriptions and click on the subscription you want to modify:
Then click on Edit subscription details:
And enter the name: