Really, why not. I kept running into things where I’d think that “hey, if I had a blog, I’d probably post something about that”. I’ve found enough useful information from other blogs that I figured why not-it’s free. I can’t promise any sort of frequency or topic consistency, but if I manage to post something that someone else finds useful at some point, then mission accomplished.
As for topics, I’ll probably have stuff on Unified Communications, Windows Development, Services, web development, sharepoint, WPF, Silverlight, or whatever else I happen to be working on at the moment. At least it’ll never get stale.