We implemented the Social eXperience Platform on Windows Azure and SQL Azure in April. We just published our Q1 (fiscal year begins July 1) availability numbers and I think they show how amazing the Azure platform is.
Our application is a stateless, RESTful web service that is used by several Microsoft.com web properties. In designing the service, we chose not to cache any data so each request is a round trip to one or more SQL Azure databases. We measure uptime at the transaction level, so if the web server or SQL Azure database is unavailable, we report that as an error.
In Q1, we served 7.76M requests with an availability of 99.995%. Our September availability was 5 9s.
Again, we chose not to write any special code to improve uptime. This is generic IIS / ADO.NET code (with the SQL Retry logic from here).
I find it amazing that a general purpose platform can deliver these kinds of results at commodity pricing levels. To achieve over 3 9s availability is generally very expensive and often requires some coding changes to achieve. Windows Azure and SQL Azure make it easy.
We are releasing a new version of SXP in the next couple of weeks with some cool new features and are already planning version 3 which moves even more capabilities to Azure. SXP is in.