protecting source code

hi,

i know in the age of open source software this question might seem old-
fashioned, but:

how do you deal with source code for commercial ruby on rails
applications?

how do you protect the source code in subversion repositories on
remote hosts?

how do you keep the source code protected when deploying a rails app
on a remote host?

how to protect source code from malicious sys admins? is that possible
at all?

thanks,
siegi