I am looking to centralise a-lot of WordPress sites, maintainability is an issue! WordPress MU seems ok, and I know it's very similar to WordPress but I'm only really just getting under the hood of WordPress after a few years, so would prefer to concentrate development purely on WordPress core. I have also read about a number of limitations that may stop me migrating my sites to MU, such as plugins and modifications.
I have just come across Virtual Multiblog when researching WordPress multiple blog solutions - it's not been around too long and I was wondering if many people are using it? I'm tied up for the next week working (yes over the holiday, nice!) but will do a local test install and have a play around with it.