WordPress MU

I'm currently evaluating WPMU and have a couple of questions.

How often do updates happen?

Generally, how long does it take to update / upgrade MU?

Thanks

hm updates come quite often, should be a page where you could see release dates and get older versions, the time it takes to update your own wpmu sites depends on alot of things, for me its about 1 second per blog perhaps(maybe a bit less), and i have about 300 blogs so far since june.

-Fredrik

Take a look here :
http://trac.mu.wordpress.org/browser/tags