According to answer on meta.stackoverflow, getting a high rep, you probably spend way too much time on the site and not getting your work done. How do they manage both?
Much of my rep is due to nothing more than time. Quite simply, given enough time even very ordinary answers can and do get rep as new people come across them. Decent answers benefit even more from time.
As for the time spent on the site, in my last job I was a one man IT department. By automating everything I could I ended up with some spare time during the day. Most of that time was spent learning new things and SF is one of the tools I use to learn. I don't answer many questions but I do read those that appear on the front page. In an average day I might visit SF 10 or more times but generally for only a few minutes at a time. Tea/coffee breaks and lunch time I also browse the questions.
Having been made redundant from that job, which was a direct consequence of said automation, I now work for myself and frequently visit SF for the express purpose of taking a break from what I'm working on, especially if I'm stuck on something.
And sometimes, an answer that you consider trivial will gain unexpected widespread attention and approval.
(Conversely, answers that you think could cause mankind to spontaneously rejoice and accept peace go almost completely ignored...)
But mostly it's just hanging out a little bit here and there.
Actually, I use ServerFault as a resource for work.
When I started the new job about half a year ago, I created my ServerFault account expressly because of the benefits it would provide me. I've lurked and dropped in occasionally for specific problems since very soon after the site went public, but there are benefits to my employer above and beyond a solution to a specific problem to my participation here.
So it's not so much that I spend too much time on the site to get my work done, but that my activities on this site are part of "doing my job." All the more so when you consider that most of my time on here (during working hours) is while I'm waiting on progress bars, or mulling over a decision that's part of the job. Sure, it's a balancing act, and it's easy to fall into the trap of avoid work via Server Fault, but at worst, my activities on here make me a better sysadmin, which is more than can be said of browsing the web, reading news, doing fantasy football and the other similar activities most of the IT folk I work with do while they're waiting on progress bars.
So I guess I don't agree with the sentiment that a high rep here (or on SO, or even SU) translates to wasted/unproductive time, and the way I manage to both get my job done and participate on ServerFault is by treating the two activities as the intertwined/overlapping activities they are.
There was a good... 7 month period there where I was rather bored at work. The ongoing budget crisis (now abating somewhat, but that's now one job ago) meant that our usual pace of new projects had come to a halt and we were pretty much doing nothing but fire-watch and deploying home-grown services.
Firewatch, as we all know, is the act of waiting patiently for something to go wrong so we can fix it. Plenty of time to do other things, such as update documentation, blog, build scripts to improve automation, and answer all the questions on ServerFault. Firewatch was very good to my rep here.
Now I have a new job, and am significantly less bored. Also, I'm a moderator now which detracts from my answering-time. And yet in the not-quite-2 years I've had the diamond I racked up over 20,000 points. How? Over breakfast (like now), evenings, weekends, and the occasional break at work when I should be doing something I don't want to do.
By now I'd gotten into the habit of answering questions. I knew what a good answer looks like, know what kind of research needs to go into them, and importantly, how to write a good-looking answer. I even asked a few questions! This experience made the few answers I was able to get in end up earning quite a bit.
It doesn't take a lot to get to high rep quickly. Earning 100 points a day, half the rep cap, gives you 700 points in a week. This is enough to get you into the top 5 earners for a week. 100 points can be 15 answers, or it can be just the right 2. Keep that up for a few months and you'll be over 10K fairly quickly.
I'm not a high rep user on SF (yet!) but I am on SU. And the answer, quite simply is, you don't need to answer all that many questions to be a high rep user. On SU, I went for one good answer a day, maybe 2. On superuser I have 1571 answers for 39,111 rep in a total of 1063 days on the site (for comparison, I have 1934 rep on serverfault for 79 answers over 718 days). At some point of time I hope to be able to answer more questions here, but its still a factor of skillset over time.
I have a few tricks - I love RSS feeds for sites I'm new to - its a good way to get a quick overview of active questions including the content of them. Many also recommend specialising in specific sorts of question.
You don't need to spend lots of time to get rep. You just need to work smart.
As for employment prospects - I think this answer is a pretty good alternate view. Its a matter of how you sell it - reputation means little, but community involvement and varied quality answers may show an enlightened employer you have skills the same way a reference would.
Finally, a smart sysadmin keeps his employer happy, and works as little as possible. I will leave the implications of that as an exercise to the reader ;).