Deploying Rails Applications: A Step-by-Step Guide by Ezra Zygmuntowicz, Bruce Tate and Clinton Begin is a good read, if a little dated. It was published in May 2008, and you can see that things have moved on a little in the Rails world since then. None the less, quite a lot of the information is still relevant and useful.
The book covers some basic Rails and version control concerns at the start, then rapidly launches into chapters devoted to Rails hosting options available from shared hosts to virtual and dedicated servers. The advice given is good and is in line with my experiences. Unix configuration is given in depth which would be very handy if you had not set up a server before. Next is a good discussion of Capistrano and automating deployments. The examples all use subversion. However, these days I expect the majority of Rails source code is pulled with Git. There is also a chapter on managing mongrels and setting up monitoring solutions. This is still relevant if you want to use mongrels, however these days Passenger is probably the best choice, and it does not have such complex management and configuration requirements. The scaling out chapter is useful and pulls together handy information including details on MySql replication/clustering. There’s a chapter on deploying on Windows and also some suggestions around performance and profiling.
I haven’t come across another book that brings together a structured collection of useful information to help you move from running rails locally to having a cluster of scalable production servers and the automated deployment process required to support it. Despite being too old to cover Git and Passenger, I’d still recommend having a read of this book if you’re at the stage of planning to launch a Rails site or looking to scale your VPS up to a cluster.