William Stacey [C# MVP] has come up with a cool cmdlet: PowerLocker. It allows you to encrypt your PowerShell scripts so you can hide your scripts from being read (and modified). He has been kind enough to provide a free "community" version that can unlock any size script. The "professional" version can lock any size script and is available for a very reasonable $20US or so. It has lots of cool options and is worth checking out.
The site also has a free tool called PowerPad.