Volta is a toolkit that enables developers to build multi-tier web applications by applying familiar techniques and patterns - namely .NET languages, libraries and development tools. Volta is what many .NET web developers have been waiting so far, especially those who don't like JavaScript.
At first I thought Volta is the Microsoft's answer to Google Web Toolkit (GWT). Yes, on one hand it is, but on the other it provides a way more. Personally I've been wondering when the .NET world will have a similar toolset and now when it is a fact I'm sure a lot of developers will like it.
Volta is not only for web. Volta is to enable multi-tier and asynchronous programming via declarative attribution and MSIL to MSIL rewriting. By Volta you can import JavaScript libraries in .NET and that's one of the things that makes Volta important. There are great JavaScript libraries out there that now can be used in any ordinary .NET application - for example you can use the Virtual Earth or Search libraries in your WinForms applications.
The main goal is to simplify the designing, building, deploying, testing, and debugging of distributed, multi-tier applications, while minimizing the amount of "new stuff" developers must learn. Volta leverages familiar, existing .NET compilers, tools, and libraries and extends them into the distributed realm.
I like that passage. I like the way Microsoft are trying to push the envelope.
If you are interested go and check out the official Volta web site in the Microsoft Live labs. There is an available technical preview that you can download and play with. Also you can find samples included in the package. Remember to visit the Volta Team Blog and to subscribe for their feed to stay up to date with the latest bits.