I'm seeing beta results from the MSN homepage again, and sweeping changes in the serps that I monitor. Even if i take out the "beta" part of the url there is a big change in the results. #1 to page two. Blah
I have been seeing some movement too. It looks to be a fairly fluid index. They must being doing updates as they are able instead of a monthly schedule or the like. It also looks like they are using an inverted index like G but hopefully without the traffic jam G has caused the internet to suffer.