Thanks for having integrated akismet spam filtering. For those interested in activating it please have a look at http://doc.silverstripe.com/doku.php?id=ssakismet
Nevertheless akismet is not enough to me to prevent all spam... could you please add by default a honeypot that would fool robots? Here's how this works... and generally quite well:
In your (contact and user-generated) forms include a field called "email" (or website, or whatever relevant) and hide it with css (display:none) and in the processing script don't continue if there is something in there and if its empty continue processing.
I have no clue how to get that validation in silverstripe, but it would be great to have in default "contact" forms and user-made forms.
(PS: copied from archive section as no one can answer there anylonger: http://www.silverstripe.org/archive/show/534?start=8#post241494)