I actually started using WPMU before the single version, but last month I finally saw the need to start up my own personal blog, to help promote my project work.
I'm using 2.3 alpha (to take early advantage of the tagging system), and a nice little business theme from AvivaDirectory. I've actually got multiple content streams running on it, since the main blog is for development posts, but there are / will be a series of project blogs that run in parallel. I'll be customising things more as I progress. Not sure how that will work out, or if I will eventually scrap it lol.
Oh yeh, blog url - voila!