We're living on the edge over here at Hi5. Our new Movable Type 4 base blog is now available at http://www.hi5networks.com/blog/
The whole company is getting involved and you'll see plenty of interesting information to come.
Also, from a technical standpoint, MT4 has proved a winner. The memcached support in Data::ObjectDriver means that we can run via plain CGI, saving a bunch of time and effort to get this up and going.
We should have 3-4 posts per week. Sadly I didn't get a chance to finish implementing userpics for MT4, but that should come shortly.