With the profile (Live ID) you used to post this question, you can participate in the MSDN and TechNet forums, the TechNet Gallery (for posting code examples), and the TechNet Wiki. All of these platforms are dedicated to discussing, asking question, or
providing articles about Microsoft products and technologies. However, as noted by Mike, only Microsoft Employees can blog (for the most part). However, you can comment and ask questions on existing blog pages.
Richard Mueller - MVP Directory Services