Subversion is a version control system. It allows you to track the
history of your source code and makes collaboration much easier, since
people can submit changes, get updates, and resolve conflicts
regardless of their physical location. Version control is an
invaluable tool in a programmer's toolbox and is definitely something
you should learn more about. http://svnbook.red-bean.com is an
excellent reference. You only need to read the first couple of
chapters to get a handle on the basics.
Many rails plugins do require subversion to install, but this one
doesn't. If the URL begins with svn://, then subversion is required.
You should run script/plugin from the root of the directory that was
generated by the rails command, not in the app directory. That is,
when you type ls or dir (depending on your operating system), you
should see app, config, lib, log, and so forth. If, after running the
plugin command, you get something like "ruby: No such file or
directory -- script/plugin (LoadError)", then you're in the wrong
The command you tried should work if you're running it from the
correct place. If it doesn't, I suspect there's probably a network
issue of some sort. Are you behind a proxy? Give us the exact error
message and someone can probably help you.