There is no shame in self-promotion
The phrase "shameless self-promotion" makes no sense when you're talking about your career.
"Shameless self-promotion" implies that there should be some sort of shame in letting others know about what you've done, and nothing could be further from the truth. Indeed, it's the only way you can be sure of getting the message out.
Have you ever had a garage sale? Did you put up a sign pointing to your garage sale? Or did you hope your neighbor would put up a sign for you, thinking "It's a good garage sale, people will tell their friends about it?" Of course not, because you knew that it was important that people know about your garage sale. So too it is with your achievements at work.
Techies seem to believe that if they do good work, they'll be rewarded. Unfortunately, "If you build it, they will come," only works in fantasy movies.
At work, your job and your career rely on the people above you in the company knowing what you do. Part of your job as employee of You, Inc. is to make sure that others know what you do, and how awesome you are. Your awesomeness may not be self-evident, or may not be understood by the people that matter. Say you've been using a new editor plug-in that helps you navigate source better, and makes your job easier. That's a cool thing you've done, because there are plenty of people out there who would write code in Notepad. You need to let your boss know about it, and keep track of it for yearly review time. It may well be worth putting on your resume, too, for your future self-promotion when you go to get a new job.
Aside from your career, if you're doing anything in open source and you want people to use your project, promoting the project is as important as writing solid code. Without users, your project is pointless. If it's a conference or meeting, that needs promotion even more. See my post on Perlbuzz "How to announce an event, or, awesome is not always self-evident" for more on the open source and conference angle.
Finally, for more on keeping yourself employed and boosting your career even in the middle of a recession, please join me and Chad Fowler for our webcast "Radical Career Success in a Down Economy" on July 1st. You'll need to register in advance. Chad and I are putting together as much as we can into our hour-long time slot. Chad's excellent new book, The Passionate Programmer, is also where I stole the idea of "your awesomeness is not self-evident", for which I'm eternally grateful.