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.