[CentOS] SSH without password on CentOS 5 ?

Hi,

I'd like to use SSH without password so I can use it in scripts (for 
example in combination with rsync to do backups). I have Carla 
Schroder's "Linux Cookbook" and I'm trying out the various receipts, but 
the one for SSH without a password doesn't work. The book is slightly 
dated, and I wonder if SSH included in CentOS works differently.

Any suggestions?

Niki