Cloud computing is considered to be safe. But as with everything in technology, a solution is as safe as its weakest link. Bruce Kyle at Microsoft has written a series or articles on Windows Azure security especially for developers. As he explains:

A series of articles about the challenges in designing your software and what you can do in your software to insure access to those who should have access and prevent access those who do not. The intent of this series is to provide a context for you to learn more and empower you to write great applications for the public cloud.

Here are links to the articles:

• Windows Azure Security Best Practices — Part 1: The Challenges, Defense in Depth.
• Windows Azure Security Best Practices — Part 2: What Azure Provides Out-of-the-Box.
• Windows Azure Security Best Practices – Part 3: Identifying Your Security Frame.
• Windows Azure Security Best Practices – Part 4: What Else You Need to Do.
• Windows Azure Security Best Practices – Part 5: Claims-Based Identity, Single Sign On.
• Windows Azure Security Best Practices – Part 6: How Azure Services Extends Your App Security.
• Windows Azure Security Best Practices – Part 7: Tips, Tools, Coding Best Practices.