I came across the need to upgrade from MVC 1 to MVC 3, skipping MVC 2 altogether. Currently, it doesn't seem like there are any formal directions coming from Microsoft. However, I found instructions mentioned in this StackOverflow question.
It appears, as of now, there is a two step process to migrate from MVC 1 to MVC 3:
1) Migrate from ASP.NET MVC 1 to MVC 2 (using this tool)
2) Migrate from ASP.NET MVC 2 to MVC 3 (using this tool)
Things to be wary of...
- ASP.NET MVC 3 Application Upgrade tool is not compatible with VS 2008* It may compile, but jQuery version changes could still break your app on the client-side
I haven't tried it myself just yet. Based on what I've read, in theory, it should work, but there will likely be minor annoyances and issues to clean up. If it seems to work the first time, something is really wrong! :)
I'll post a follow-up once I give it a go.