SubVersion is a modern VersionControlSystem that aims to replace CVS. Of the numerous CVS replacements, SubVersion is quite possibly the most similar to CVS in CommandLine interface and has a stable support community, making it a good choice if you wish to move away from CVS.
The CommandLine client, analogous to cvs(1) and with very similar use for the most part, is called svn. svn help provides a list of all commands and global options. svn help command provides help about the specific command. Unfortunately, there is no ManPage to speak of.