I think this blurs the line between your personal blog and the company sponsored community site.
I can't speak to you using company assets for your personal use, since you've mentioned before that you aren't paid to blog per se, that's something for your boss and bosses boss to work out and doesn't matter to me or anyone not working at Microsoft. It's
not like Microsoft isn't already sponsoring space for employees personal use (e.g. blogs.msdn.com), but creating a thread in a community site for your own use seems a little out of bounds to me. Meaning that it seems odd to me.