On June 7th, Microsoft is holding a “Meet Windows Azure” event, which promises an update on the future of the platform-as-a-service cloud. Microsoft’s keeping mum on what we can expect, but rumor has it that Corporate Vice President Scott Guthrie and company will be debuting the long-awaited Antares application framework and Linux VM.

Both of these would be extremely strategic cloud moves for Microsoft. Antares – a web/application framework that supports various languages and stacks – is hypothetically designed to be deployed on top of Windows Server as well as on the Azure cloud, giving enhanced application portability between public and private environments. That’s key to Azure’s hybrid play. And if Antares follows through on the promise of going outside the .NET framework for open source stacks and languages, it could see a lot of developer interest.

Similarly, the Linux VMs that have been long in coming to Windows Azure would bring infrastructure-as-a-service components to the platform, a capability conferred by the ability to run persistent virtual machines in Microsoft’s cloud. A nice side effect would be the ability to host SQL Server or SharePoint Server in the cloud. And it would bring Windows Azure into a more directly competitive position against Amazon Web Services, which is working hard to complete its own dominance of the entire cloud stack.

ZDNet’s Mary Jo Foley writes that this is a nice start, but there are still some gaps in Azure’s offering: Tighter Azure integration with Active Directory, for example, the ability to start a VPN between on-premises Windows servers and Azure, or the long-promised SQL Azure Reporting Services would all boost Azure’s developer and enterprise friendliness.

For my money, I’m most interested in Antares. A unified application framework across cloud and private environments may be just what the doctor ordered, especially coupled with Microsoft’s newfound friendliness to open source technologies in the cloud. Either way, we’ll see what Microsoft has to say for itself on the seventh.