Greetings,

 >> Can someone advise me how to deal with comment spam?
 >
 > I'd be interested in this as well.

Effectively dealing with comment spam will require some tweaks to the 
comment system:

1) Change the HTML so that all user generated links get a ref='nofollow' 
attribute.  This makes the link worthless for SEO/Pagerank purposes 
because Google will never follow it.

2) Use a captcha for comments.
CPAN has one offering that I've used with great success on my forums - 
GD::SecurityImage.  There were a couple gotchas with caching and reverse 
proxies but aside from that this module was fairly straightforward to 
get working.  So far, it's cut out all forum topic spam on my site.

Image captchas are NOT accessible to those who are vision impaired! 
This is a huge minus to their use. The fancier implementations generate 
audio captchas too; sadly, GD::SecurityImage is not a fancy implementation.

We could also graft in support for captchas.net and let a third party 
handle the whole mess instead.  They support audio captchas and have a 
CPAN module for easy integration.  While they are free, I wonder how big 
of a site they would support before getting pissy?  We'd have to talk 
with the maintainers before we went this route.

 From what I can tell, both of those "features" are pretty much the 
proven best-practices for eliminating comment spam.

See Also:
http://googleblog.blogspot.com/2005/01/preventing-comment-spam.html
http://www.captcha.net/
http://captchas.net/
http://search.cpan.org/~burak/GD-SecurityImage-1.61/lib/GD/SecurityImage.pm
http://search.cpan.org/~geoff/WebService-CaptchasDotNet-0.06/CaptchasDotNet.pm

http://photographica.org/forums/photo_feed <- uses GD::SecurityImage for 
new topics.

--
Cory R. King
Mozi Media Group, LLC.
http://www.mozimedia.com