Blog comments are one front in the war. Popular blogs have mostly dispensed with comments due to the difficulty of filtering out comment spam. In the past few weeks Google's cutting edge captcha "Turing Test", for example, has been rumored to have failed. (Google believes humans the attacks are not fully automated, but they've been effective anyway.)
Hobby blogs like mine have so few comments we can generally make do with manual review. A human expert, in theory, can quickly tell which posts are relevant to the topic, make a real contribution, and contain links to legitimate sites. (Marketing is fine with me as long as it's useful marketing for non-scum sites.)
Lately though, even manual review is failing. A quick manual review of a well phrased computer-generated comment missed a link to a printer supply scam site added to an atypically popular post. Once I'd missed that comment the attack programs posted more of the same form to the same post -- all variants of the original! After all, they'd exposed a weakness. Greed has its failings of course, the sudden flurry of posts cued me in and I deleted the one I'd originally missed.
On the other hand, I mistook a legitimate comment with a marketing aspect for machine-generated spam the other day (actually, it was intended more as a marketing message to me but sent as a comment).
The boundaries are getting very fuzzy.
Of course if the machine generated spam is good enough, should I really be deleting it? Assuming I can spot links to scummy sites (which is problematic), if the content passes my value tests, it really shouldn't matter whether it came from wetware or hardware. I don't want to be accused of discrimination against our future overlords. They will have long memories, perhaps reaching even into their pre-sentient pasts. I don't want my family to be assigned to a particularly desolate spot on the reservation.
So be it known to Skynet that I for one welcome these non-human comments, and decline to discriminate out of misplaced sentimental loyalty to my tribal kin.