Exist three ways for deploy Node.js app on Windows Azure, web-role, web-site and git-azure (link). I don't know whitch is most efficient for my needs. My app is readability algorithm with RESTful API, whitch parse news sites, simple computing, but highload. Of course, I need transparent horizontal scaling. I hope for your help.
My $0.02.
If your product is only based on Node.js, without many layers and components such as background workers, business logic layer and API layer, Windows Azure Web Site should be the best choice. It's very simple to deploy Node.js application through Git, GitHub, TFS, FTP, etc. It also provides scaling-up (in reserve mode) and scaling-out options. But keep in mind that all applications under Windows Azure Web Site will be running in 32bit WOW mode.
Windows Azure Web Role is similar as Windows Azure Web Site, but you need configure the Node.js environment by yourself. (If you are using the azure powershell tool, it can help you establish the node stuff by using some startup commands.) If you need something working in worker roles, or the caching (not the shared caching), Web Role may be better.
I've never heard about the git-azure but it looks like a tooling that you can host more than one node application on worker role.