From SpamAnti.net

New technique observed [ed. note - I've noticed this new techique in use, though as my e-mail program of choice does not display HTML it makes this sort of spam immediately noticeable.]
Apparently, there is a new technique used by spammers. It is becoming a little problem since the simplest keyword-based filters do not detect these messages as SPAM. The text is riddled with random HTML comments breaking all words in smaller parts while leaving the message still readable by Outlook Express users.

This should lead to a new evolution of counter-measures and filter programs.