There is a new Bagle variant making the rounds.  Seems to be spreading slowly.  Email arrives with a .zip attachment that is encrypted with a password.  The password is stored in an image file that is also an attachment.  Anti-virus software that looks for the password in the text won't find it.  More details here: http://www.sophos.com/pressoffice/news/articles/2006/06/baglekl.html