I got my current job through LinkedIn too. Hadoop / big data position. I've got quite a few recruiter spam type messages though, but the one I got the job through was an in house recruiter for the company. I figured they were just doing key word searches as my profile isn't anything special. In my profile I put a good paragraph about each of my past positions highlighting experience with the technologies I wanted to work with. 5 or 6 months later this job came up.

Out of the blue? Or was the recruiter already a second or third relation to your contacts?

I'm just wondering because linkedin seems to have pockets of good people and then pockets of spam recruiters. Right now I'm in the spam trap and 90% of my traffic is boilerplate recruiter spam. I'm not sure how I'd get myself noticed by good recruiters like this.