Looking at the project.json file in this question and looking at other questions on SO about RC2 makes me think that RC2 has been released. But I cannot find any official announcement that it has been released. Does anyone know if it's been released? If so, can you install it on top of RC1 or are there special installation procedures?
ASP.Net Core RC2 will in all likelihood be released on or before 5/17/16 as Damian Edwards mentioned at the ASP.Net Community Stand-up on 5/10/16. As to the link you referenced, they are using nightly builds. You can actually get bits now from the nightly stream that are labeled "Microsoft.AspNetCore.Mvc": "1.0.0-rc3-*" as the team has continued to finish polishing things up for release. These ports will end up being renamed to whatever management decides to call the final build. The Nuget server for Microsoft Nightly builds is https://www.myget.org/F/aspnetcidev/api/v2/ You can add it to Visual Studio by going to Tools=>Options=>NuGet Package Manager=>Package Sources.See NuGet Package Manager Image Here. However, being so close to a supported release version, it seems futile now. I assume Microsoft will support RC2 with a "Go-Live" license.