I just downloaded the new LinkedIn Outlook Connector that brings my “LinkedIn Professional Network tight within my Microsoft Outlook Inbox.”

That may not seem like a hugely significant development, but as I have noted many times previously, I think LinkedIn is slowly (and perhaps not even consciously) starting to become a global business backbone directory.

Okay, you’re probably wondering right now what I mean by “backbone directory.” I’ll admit I am not entirely sure myself, even though I know I am right! What I increasingly see is LinkedIn playing a supporting, background role within a growing number of directory products. Typically, those directories let you easily connect a person listed in their directories to your professional network on LinkedIn. It’s an easy way to see how you might be connected to somebody, which is wonderful for salespeople. It also lets you readily peruse an individual’s LinkedIn profile, more times than not a current and detailed resume and an indicator of who they are based on who they know.

Where I see particular opportunities for LinkedIn is in professional services buying guides. What better way to pre-screen a prospective lawyer, accountant or financial advisor than by quickly determining who you might know in common so that you can get a trusted opinion?

But back to my Microsoft Outlook inbox. After installing the LinkedIn connector (you must also install the Outlook Social Connector from Microsoft), I got a glimpse of what the future might hold. When you view an email from someone with whom you are connected in LinkedIn, you see their LinkedIn photo right along the message. There is also a new window that almost instantly organizes all your emails to and from that person along with your prior meetings with that person. You can also quickly isolate email attachments received from that person, making it easy to review documents that person had sent to you. In short, my email inbox has become an entry-level CRM system. I also have easy access to the email addresses of everyone in my LinkedIn network each time I send an email.

Actually, the information being pulled from LinkedIn right now is pretty limited. But start thinking out a bit. There’s no reason I couldn’t filter and prioritize my emails based on whether or not the email sender was in my LinkedIn network. Indeed, what if LinkedIn was to supply me with information on anyone who was in LinkedIn, whether or not the person was in my network? Imagine seeing a photo, company name and title, and information on who you know in common on more, if not most, of your incoming emails? There’s information value, to be sure, but there’s also a “trusted sender” play here. Yes, LinkedIn could be used to validate the integrity if not the identity of email senders. You might even someday filter out email from anyone without a LinkedIn record. Push this out a bit further, and you can see a day where you need a LinkedIn record just to be in business. At that point, LinkedIn’s position as a “backbone directory” is secure, and the revenue opportunities are many and huge.