As much as I dislike Microsoft — mostly their business practices, although I’ve lost too much work to Word over the years to trust it — I have to admit it’s pretty cool that they let employees blog about what they're doing at work. For example, Brian Jones discusses the development of the XML-based file formats in Office 12; Cyndy Wessling covers the PDF output capabilities of upcoming versions. (If Visio ends up creating decent PDF, there will be a lot of happy FrameMaker users out there.)
For a view of the corporate culture, Mini-Microsoft recently hit the “blogs of note” list and provides an unvarnished look at the ossification of a large corporation as it happens. I’m sure there are other blogs about Microsoft by Microsofties... if you run across any, leave a link in the comments.