Complete interview with H.D. Moore http://www.securityfocus.com/columnists/439
Metasploit 3 supports evasion options for almost every module. The evasion options are broken down by protocol and can be seen with the "show evasions" command in the console interface. A module that uses the SMB, DCERPC, and TCP protocols can benefit from over 15 different evasion options.
One of the great things about the structure of Metasploit 3 is that adding a new evasion method rarely requires the modules themselves to be updated. It's even possible to develop a loadable plugin that implements new, unpublished evasion routines (and sell it, if you wish to do so).