Just a quick prompt to hear what other folks think of the Network option that replaced WPMU.
I've set it up and have been working my way through a few issues with DNS for independent domains (rather than as sub-domains or sub-dirs of the primary) but I can see that once I figure out the process, this will be quite handy. Especially when applied to a network of sites that have a similar theme/topic and could benefit from drawing on the same database for ad delivery.
While I haven't tested this yet it seems that copy could be posted on more one site if users have permissions on the other sites.
I'm having a bit of fun with this because it opens up some doors that I hadn't considered before.