In one of my niches I am fighting for rankings with a fairly spammy company. This company has about a dozen very similar websites all cross linked together. Since the websites are so closely related this cross linking results in very relevant back links. What can I do about this? I'm pretty sure Google would consider this spam, but they are not noticing this problem on their own. Can I report this as spam somehow? Is there any other way I can bring this to Google's attention?
If Google thought this was a link farm, they would already be penalised - or at least the links would be devalued.
Not if they were smart enough in making each website seem like a separate identity. Google is not smart enough to catch all spam. A lot of it has to be manually reviewed to be caught.
Report it and wait for a confirmation of report @ your webmasters tools (assuming you use it and insert your email upon report).
I would just do it anyway without much ado and facilitate with all the info that they need. As usual it will take time for the investigation and action to take place. You are right to say that usually they will make it as if each site is not related to one another but anyway, it's still worth to try.