Up until now the only way to be able to deploy Sandboxed Visual Web parts was to use the Visual Studio 2010 SharePoint Power Tools. Yes, there were some restrictions while doing so.
The Visual Studio 11 Developer Preview adds the following improvements
· Sandboxed Visual Web Parts
· Improved support for Sandboxed solutions
· Remote publishing
· New designers for lists and Content Types
· New Site Column Project Item Template
· New SilverLight Web Part Project Template
· Support for ALM ( Application Lifecycle Management )
All the details for these improvements are available at the Product Highlights for Visual Studio 11 Developer Preview.
These are certainly welcome improvements!