As the start-up describes itself, SocialMedia “is the leading provider of social-platform services. It fuses together three core features–management, marketing and monetization–into a comprehensive package that advertisers and developers can use to grow awareness, and grow their applications on social platforms.”

Translation: It sells the picks and axes and maps and other needed stuff to the widgeteers of this particular digital gold rush around the hyped social-networking space.

And you know who always makes most of the money in a gold rush? The seller of picks and axes and maps, that’s who!

And, in fact, SocialMedia is profitable, by selling its services to help third-party developers on social networks like Facebook. That includes conducting detailed analytics of the activity of widgets and forming an ad network on the space, based on data collected.

While powerhouse companies like Google have recently talked about the difficulty of making money from social networking, Goldstein, a longtime entrepreneur, thinks the market can better be cracked by new companies like his that understand the new medium.

He’s gotten $3.5 million in backing to do that from savvy investors, like former AOLer Jim Bankoff, entrepreneurs Ted Barnett and Marc Andreessen, as well as VC outfits like Charles River Ventures.

I make a lot of fun of widgets–more to come soon!–but I think Goldstein is a very sharp operator and brings much -needed seriousness and business acumen to a very juvenile market. As in: Adult supervision.

Here’s my visit to SocialMedia and interview with Goldstein (who, by the way, is married to another Web exec, Tina Sharkey, who heads BabyCenter and whom we video-visited here):