Really rather good Microsoft webcast on Azure and its licensing. Useful takeaways:

• pricing comparison (the Azure list price will always be the same as Amazon Web Services, and the Azure EA price will always be lower);
• how to purchase Azure in an EA (make an upfront payment, pay any additional usage either annually – for up to 50% overage – or quarterly for more than that);
• how existing EA customers are impacted (overage penalties go away immediately, existing quarterly payments remain in place with annual payments starting at renewal).

This webcast was originally aimed at Enterprise customers in the US and the licensing portion starts at 13:49 but I’d recommend the whole thing if you want to get a handle on the positioning of Azure too. http://bit.ly/19lQ5uq