This post on the 7 Sins of Self-Promotion on Twitter actually provides a great foundation on thinking about how you use any social media or present your personal brand (online and offline). I particularly found the further link to the twictionary helpful, and reminds me of how many times I've learned about LinkedIn from other users, to supplement the updates and tips from the LinkedIn blog. Where do you keep up with these trends? And how are you using them to integrate into your job search and the development of your professional image?