Ineffectiveness of fuzzy checksums?

For the past 6 months to 1 year I've noticed that the fuzzy checksums don't
catch many of the particular devious spamming techniques.  (i.e. completely
random hostnames and URLs combined with garbage HTML and all the other
tricks).  If it weren't for greylisting, I'd be drowning in spam.

Is there any intention to come up with a new checksum that is somehow
resilient to these techniques?  I'm afraid that once we lose the next battle
in the arms race (the spam zombies implement SMTP correctly and get past
greylisting) I'm going to have a mailbox full of spam again.