I think there's a correlation between "just updated my LinkedIn profile" and "I am about to change jobs".

It is for this very reason that I update my profile regularly, even if insignificant ways. I actually have a Google Calendar to remind me to do it twice a month.

This can be great for your career.

If you don't work for a itty bitty startup you can count on someone above you in the org chart catching wind of every LinkedIn update you make. I have been asked about my frequent updates twice at my current job; the second time they were so concerned that I was looking around for a new position (and I had just taken a crucial role in a new project) that they offered me an unasked-for performance bonus following the completion of the project. It totally floored me.

I too have a linkedin account that's been languishing. I recently went through and added people I've been working with closely over the last year from my email and phone contact lists. Amazing how fast I grew my connections in just a couple days.

I think that this is probably how it's supposed to work. Long slow periods, punctuated by quick rapid action while people do spring cleaning.

My (unscientific) observation is that LinkedIn activities varies with age demographics. LinkedIn contacts and info are actively updated by the over ~30 crowd. Under 30 crowds tend to have less distinction between work/friends thus work contact info is done on facebook (or other general soNet).