While LinkedIn has moved overcautiously in rolling out its applications platform, and the majority of Facebook's 28,000 apps still lack business value, there's evidence that both sites want to harbor more social networking tools that help us do our job — and it's about time.

During the last couple years, the discussion around the productivity that social networking technologies could yield was framed too narrowly. On one hand, people said you should own a LinkedIn account for work, and a Facebook profile for your personal life.

There was also a third option, specifically on the work side. Many companies blocked social networks like Facebook at work and provided their employees with internal social networks behind the firewall. These business networks were built by incumbent vendors like Microsoft (with the Web 2.0 features in SharePoint) and IBM's Lotus Connections. We also saw a bunch of Enterprise 2.0 vendors — companies that built Web 2.0 software such as blogs, wikis and social networks specifically for businesses — emerge during this period as well, including Socialtext, Jive, Mindtouch and Awareness (the list goes on, and I can't mention everyone).

But the way to derive business value from social networks should be just one of these options: it needs to be all of them working together and feeding (or streaming, to use the latest Web 2.0 term in vogue) information into a central portal, preferably of a user's choosing.

LinkedIn and Facebook made announcements during the last couple weeks that indicate they want their sites to be a platform for application development of productivity-based applications. The former was never really in question, since LinkedIn is undoubtedly a social networking site aimed at professionals, but they did take their time rolling it out.

When LinkedIn launched their application platform, it set loose nine applications built by Web-based vendors, including Google and Amazon. Some of them were wonderfully utilitarian, including ways to store files online (through Box.net) and sharing PowerPoint presentations online (from Google).

For LinkedIn's part, I applaud the move, but it's not aggressive enough. While I appreciate the fact they want to avoid the Wild West mentality of Facebook and MySpace to maintain their professional look and feel, nine applications in these times of fast Web development are pretty slim pickings. But they have to start somewhere, and moving too aggressively might upset their audience.

I was (pleasantly) surprised by Facebook. The company announced last week that it would provide a tookit for Force.com, the platform owned by Salesforce.com that allows people to build Web-based business applications. Using this toolkit, Facebook's COO Sheryl Sandberg told attendees at Salesforce.com's Dreamforce conference last week, would allow people to build business apps on Force.com and move them to Facebook.