I am the Farm Administrator of a SharePoint 2010 farm for a relatively large organization and we often get requests to deploy site templates found throughout the web. We are still a very small team supporting a large number of users and sites. The difficulty with these requests is that the solutions found are typically farm solutions which require the solution to be available to all site collections within the Web Application. This wouldn’t be an issue, except we are unable/unwilling to support all of these solutions, both in technical and education/training terms.
I have found the easiest solution is to deploy the solution to our DEV environment, deploy a site using that new site template and then I save the site as a template. I can then import that .wsp solution file into a new Visual Studio 2010 project using the very helpful instructions below. I cannot claim any credit for these instructions, however, only credit in finding them.
Don’t forget to create the new solution as a Sandboxed Solution as opposed to a Farm Solution. I would also highly recommend you are clear with your users/customers that these solutions are not supported by your organization and document the transaction so as to protect yourself and your time. This option will be useful if the solution is to be deployed to a Site Collection. You could just use the exported .wsp file but I like to rename the feature within Visual Studio and package it to look a little more official.