A very good white paper has just been updated on Office Technet for MOSS:

 Data protection and recovery for Office SharePoint Server in small to medium deployments

http://go.microsoft.com/fwlink/?LinkId=102839&clcid=0x409

 See also Brian's blog article

http://blogs.msdn.com/brismith/archive/2007/10/24/backup-and-restore-what-are-the-options.aspx

Updated in June 2008: Now covers Farms of any size.