(Isn't that how you're supposed to start anything computer-related?)
My name is Jensen Harris and I work on the Microsoft Office "user experience" team.  Our team is responsible for the overall interaction and visual design of the programs that ship in Office.  Although we work very closely with the individual application teams (Word, Excel, PowerPoint, Outlook, etc.) to help solve difficult usability issues specific to those programs, our key responsibility is to design and develop the UI framework that people use to interact with all of Office.  Some of the innovations that came from this team before my time working on it included red-squiggle spell checking in Office 95, command bars in Office 97, and Task Panes in Office XP.
In short, the team's mission is to help make sure that you can find and use the functionality in Office as seamlessly as possible.
Some background on me: I've worked at Microsoft for a bit over seven years; before that I was twice a summer intern.  I spent my first five years at Microsoft working on the Outlook e-mail and PIM program, both for the Macintosh and for Windows.  The last project I worked on was leading the redesign of the Outlook 2003 user interface that shipped in Office 2003.  After work on Office 2003 concluded, I moved to the overall Office user experience team, and that's where I've worked for the last two years.
In this blog, I hope to write a lot about my thoughts about the ins and outs of defining and designing the user experience of Office.  I'll be writing frequently about the future of Office but also sometimes the past.  And there may be times I find it irresistible to delve into general user interface issues or even (gasp) software issues in general.  Hopefully you'll indulge me once in a while.
I look forward to reading your comments and hearing suggestions on what would you would like to see me cover.  In some cases, I may be able to point you to blogs which more precisely cover the information you're looking for; there are a pretty substantial list of product teams and personalities blogging from around the Microsoft world these days.
More from PDC in Los Angeles tomorrow...