Fortune 500 company jumps on board the social media bandwagon… you’ve heard that one, right? Fortune 500 company uses social media to promote its sustainability credentials… that’s also old(er) news. According to Sustainable Life Media, Toyota’s trying to take this narrative to the next level by joining forces with Federated Media’s HarmonyTweets.com, a Twitter aggregator focused on connecting users with “innovation and inspiration updates from charitable organizations, industry leaders…, and sustainability-minded individuals.” The site’s Prius community not only gathers Tweets labeled with the #prius hashtag, but also provides a feed of blog reviews of the 3rd generation of the vehicle, and news from Toyota.

Toyota’s use of the site to position itself couldn’t be clearer: the Harmony Tweets Prius community is centered literally between “inspiration” and “giving” (the site’s two other communities) on the home page.

The concept certainly seems sound: Toyota can further align the Prius brand with values likely held by its core market. It’s also partnered with one of the most innovative player in the world of web marketing: Federated works with, or has worked with, some of the online space’s biggest players, including Digg, Boing Boing, and TechCrunch.

Despite those strengths, I have to wonder about the value proposition here — can a site dedicated mainly to bringing together content from another source play a significant role in building brand value? Will the conversation leaders in the sustainability and social media spaces find such a service compelling enough to support it? Does Twitter’s flexibility, which allows users to access the service from a variety of applications, lend itself to this kind of centralization… even around a niche?

We’ll have to wait and see. In the meantime, what do you think? Smart use of social media, or a well-intentioned experiment that may not have the legs to get going…?