This morning ReadWriteWeb Vice President of Content Development Marshall Kirkpatrick announced that he is stepping back from full-time involvement at the popular tech blog and launching a new startup called Plexus Engine, which will help surface relevant information about various topics.

Kirkpatrick has been using custom social media intelligence tools to find stories for ReadWriteWeb for years, and he’s been building and providing some of these tools to consulting clients such as EMC Greenplum as well. The PR firm Jones-Dilworth is already using Plexus, for example.

I got an early look at the product, and while I’m not at liberty to disclose any details I will say that it will compete with a social media company that’s already generating a lot of buzz. The product is dedicated to taking the grunt work out of certain social business activities.

Will it be useful? Well, the folks at Jones-Dilworth say it is. Kirkpatrick quotes founder Josh Dilworth: “We are already using Plexus at Jones-Dilworth and it makes us look smarter every day. It’s instant domain knowledge — ideal for getting up to speed in new categories.”

I’m more skeptical. I see a lot of these sorts of tools, all of which claim to provide some sort of actionable intelligence from social media. Other than responding to customer complaints on Twitter and Facebook, I’ve seen relatively few truly useful applications of social media mining. Companies like Klout are trying to change that, but are pushing some major privacy buttons as they do so, while offering questionable business value. Maybe I’m just feeling grouchy about social business tech at the moment because so many of its promises are going unfulfilled. That said, I haven’t had deep hands on experience with Plexus yet, and Kirkpatrick is coming at this as a practitioner, so it’s worth keeping an eye on.

If you want to find some hints as to what Plexus may end up doing, check out Kirkpatrick’s keynote at CyborgCamp.

Disclosure: I worked for ReadWriteWeb, but not directly under Kirkpatrick.