The new and much improve download page for the Windows Azure SDK (http://www.microsoft.com/windowsazure/sdk/) has links and a history of all the older releases. It's missing the CTP releases since they are no longer supported in our production environment. I thought I'd put together a complete list of SDKs including CTPs since the first CTP way back in October 2008 (hotfixes not included)
Admin access, Full IIS, Remote Desktop, VM Role CTP, improved Diagnostics, Windows Azure Connect CTP
First Official Production SDK,Win 7 Support, Introduction of Windows Azure Diagnostics, Inter-role communication
VS2010 Beta Support improvements to devfabric/devstore
The first SDK release at PDC 2008
What you can see is that we've been pushing out roughly 3-4 SDKs a year. I've had the luck to be on the team since the first SDK release in 2008. In the process, I've learned many things around versioning/compatibility, servicing, live site support, test prioritization and a few things about cloud computing as well.
I'll try to share some of what I've learned in those areas over the next few posts. Please, stay tuned.